UC-NRLF 


C    2    103    271 


LIBRARY  o? 

OF  ZOOLOOV 

.  •  -    • 


NEW  SERIES,  VOLUME  I,  PART  VI. 


MONOGRAPHS  OF  THE   PACIFIC   CETACEA. 

II.  — THE  SEI    WHALE   (BALMNOPTERA   BOREALIS   LESSON). 
2.    ANATOMY  OF  A  FCETUS  OF  BAL^NOPTERA  BOREALIS.     BY  H.  VON  W.  SCHULTE. 


[389] 


f/7 


BIOLOGY 

LIBRARY 

G 


',•-'','    '-•         * 
•'•':':•  •'•'•'•  •':- 


Lib. 


ANATOMY  OF  A  FCETUS  OF  BAL^NOPTERA  BOREALIS. 
BY  H.  VON  W.  SCHULTE. 

*• 

PLATES  XLIII-LVII. 
CONTENTS. 

PAOE 

INTRODUCTION                                                   304 

MEASUREMENTS  one. 

•  oyo 

EXTERNAL  ANATOMY                          ....  399 

Coloration ggg 

Hairs                  •                 399 

Outline      •                                                                                                                399 

Head                                                                                                                         401 

Eve  •                                                                                                                401 

Ear    •                                                                                                                                                  ....  401 

LlPs                                                                                                                                                     ....  401 

Naso-vomerine  organ 402 

Flipper      .                                                            402 

HumP        •                                                                                              403 

Vulva                                                                                                                        403 

Anus 403 

MYOLOGY 403 

Panniculus  carnosus           .............  404 

Cavum  ventrale         ...                 40g 

Musculature  of  ventral  pouch    .         .         .   406 

Sterno-mandibularis  and  associated  muscles .         .         .  409 

Muscles  of  mastication 410 

Facial  muscles 412 

Extrinsic  muscles  of  eye 414 

Muscles  of  tongue ,  415 

Infrahyoid  muscles    ...                           ..                  ....  416 

Suprahyoid  muscles 417 

Trapezius  complex .  417 

Ventro-appendicular  musculature      ........                  .  41g 

Trachelo-costo-scapular  muscles        .         .                 ......  419 

Rhomboideus    .        .  4.10 

•                  «                  •                  •                 •  Tt  A  tJ 

Scapulo-humeral  muscles  ........                  .  419 

Intrinsic  muscles  of  flipper 42Q 

Abdominal  muscles .  421 

Pelvic  musculature 423 

Intercostals .  433 

Diaphragm                          - .                 ...  423 

Hypaxial  musculature        .........  424 

Dorsal  musculature  .         .                 ...                          .  427 

Spino-costal  muscles .  427 

Spino-dorsal  muscles          .                                                                                           ...                                    .  427 

UPPER  ALIMENTARY  TRACT      .                .                        _  431 

Cavum  oris  proprium         .                 ...  431 

Fauces ...                 .  432 

1391] 


392  SCHULTE,  SEI  WHALE. 

PiQE 

Pharynx .433 

(Esophagus 434 

RESPIRATORY  PASSAGES •      435 

Nasal  fossa.     By  John  D.  Kernan  Jr.  .      435 

Larynx .430 

Thryoid  cartilage       ....  •       43(5 

Laryngeal  sac •  •  •       437 

Trachea .437 

Bronchi .438 

THORAX .438 

Pleurae .439 

Lungs        .  .439 

Pericardium •       440 

Heart         ....  .441 

Thymus .443 

Thyroid     ....  .444 

ABDOMEN •      444 

(Esophagus        ....  .445 

Stomach 445 

Duodenum •      448 

Jejuno-ileum      ....  .  .      449 

Colon .450 

Ccecum ....      450 

Liver .450 

Pancreas    ...  .  .      453 

Spleen        .  .  454 

Adrenals .  .         .       454 

Peritoneum .  454 

UROGENITAL  APPARATUS 459 

Kidneys .       459 

Ureters 461 

Bladder     ....  .461 

Urethra     ....  .462 

Ovaries      ....  .  .  .      462 

Oviducts    ...  .463 

Uterus       ....  ...       463 

Ligamentum  latum    ....  463 

Vagina •  464 

ANGEIOLOGY     ....  .  465 

Arteries 465 

Venous  system  .  .  466 

CERVICO-BRACHIAL  PLEXUS      .  470 

Cervical  plexus          ....  .  470 

Brachial  plexus          ...  .  471 

SKELETON '  473 

Skull          .  .      473 

Norma  occipitalis        .  474 

Norma  verticalis  .  .  475 

Norma  basalis 475 

Norma  lateralis 478 

Orbit          ...  .         .         .         .         : 479 

Cranial  Cavity 480 

Mandibles .483 

Hyoid         .  483 

Vertebrae 484 

Cervical  vertebrae 484 

Axis 487 

Ribs 487 

Sternum .  489 


SCHULTE,  SEI  WHALE.  393 

PAGE 

Pectoral  limb .  439 

Scapula  .  .  489 

Humerus 489 

Radius 490 

Ulna  490 

Carpus  . 490 

Digits  491 

Pelvis 491 

THE  EAR.  By  John  D.  Kernan  Jr. 492 

Meatus  auditorius  externus 492 

Cavum  tympani  ...  g .  493 

Tuba  auditiva .  493 

Ossicula  auditus  ...  ...  493 

Capsula  otica .  493 

Pars  cochlearis .  .  494 

Pars  canalicularis .  .  495 

Canalis  facialis          .............  496 

Tegmen  tympani  ....  .  497 

ILLUSTRATIONS .  493 

Plates  498 

Text  figures .  499 

LIST  or  WORKS  CITED 500 


394  SCHULTE,  SEI  WHALE. 


INTRODUCTION. 

The  foetus  described  in  the  following  pages  was  taken  by  Mr.  Roy  C.  Andrews  at  Aikawa, 
Rikuzen  Province,  Japan,  on  July  5,  1910.  Together  with  several  other  foetuses  of  other  species 
of  Balcenoptera  and  of  Megaptera,  also  collected  by  Mr.  Andrews,  it  was  entrusted  by  the  Ameri- 
can Museum  of  Natural  History  to  the  Department  of  Anatomy  of  Columbia  University  for 
purposes  of  anatomical  study.  At  the  time,  the  summer  of  1914,  the  wish  was  expressed  by 
the  Museum  authorities  that  the  foetus  of  B.  borealis  should  form  the  subject  of  an  anatomical 
report  to  the  Museum,  which  might  be  published  in  conjunction  with  Mr.  Andrews's  monograph 
of  the  species.  It  is  difficult  to  overestimate  the  importance  of  material  of  this  sort  from  a 
diminishing  species,  of  which  I  am  not  aware  that  a  foetus  has  previously  been  procured  and 
preserved  for  laboratory  examination.  For  this  unusual  opportunity  and  for  many  courtesies 
in  the  course  of  the  work,  I  owe  most  grateful  thanks  to  the  officers  of  the  American  Museum, 
and  in  particular  to  Mr.  Andrews  for  the  great  assistance,  which  his  knowledge  of  the  adult, 
most  generously  placed  at  my  disposal,  has  rendered  in  the  whole  progress  of  the  study.  To 
Professor  Huntington,  under  whose  oversight  I  have  prosecuted  this  investigation,  I  would 
express  my  deep  appreciation  of  his  interest  and  advice;  his  experience  has  been  invaluable  in 
securing  a  fuller  utilization  of  the  material,  his  judgment  on  occasions  innumerable  has  cleared 
up  difficulties  both  of  fact  and  interpretation.  The  illustrations  are  the  work  of  Mr.  M. 
Petersen,  Artist  to  the  Department  of  Anatomy.  Their  production  has  been  a  labor  of  infinite 
care,  most  of  them  have  been  studied  and  drawn  under  a  lense,  and  for  their  finished  accuracy 
of  detail  I  am  under  great  obligations  to  the  patience,  skill  and  intelligence  of  the  artist.  Dr. 
John  D.  Kernan,  Jr.,  of  this  department  has  undertaken  the  description  of  the  nasal  fossa  and 
the  ear. 

The  foetus  measured  375  mm.  linear  length  from  the  tip  of  the  rostrum  to  the  notch  in 
the  flukes.  Immediately  upon  being  taken  it  was  placed  in  a  large  receptacle  of  alcohol,  the 
abdomen  and  thorax  having  been  previously  opened  by  a  small  incision  in  the  linea  alba.  In 
a  few  places,  the  diaphragmatic  surface  of  the  liver  and  the  dorsum  of  the  ligamentum  latum, 
the  fluid  seems  to  have  penetrated  slowly,  for  these  surfaces  are  pitted  by  minute  bubbles  of 
gas.  The  cerebrum  also  has  largely  disintegrated,  and  the  surface  of  the  left  lobe  of  the  liver 
was  friable  and  became  damaged  superficially  during  its  removal.  Otherwise  the  viscera  were 
successfully  hardened  in  situ  and  retained  clear  impressions  of  adjacent  organs,  so  that  an 
unusually  favorable  opportunity  was  afforded  to  study  their  syntopy.  For  transportation 
and  storage  the  foetus  was  placed  in  a  cylindrical  jar,  in  which  it  acquired  a  marked  spiral  twist 
to  the  right.  This  attained  a  maximum  in  the  thorax  and  here  the  ribs  of  the  right  side  were 
bent  in  lateral  to  their  angles  with  consequent  deformity  of  the  right  lung  and  disturbance  of 
thoracic  proportions.  There  was  also  considerable  desquamation  of  the  epidermis  and  several 
small  areas  of  inconsiderable  'surf  ace  "damage.  On  the  whole  the  sum  of  the  defects  is  very 
small  for  material  obtained  and  transported  with  such  difficulty,  and  its  great  merit  consists 
in  the  admirable  preservation  of  its  muscles  and  viscera. 

Accordingly,  with  a  view  to  using  it  to  the  best  advantage,  attention  was  concentrated 
upon  the  myology  and  visceral  anatomy,  and  in  this  latter  field  primarily  upon  the  topography 


SCHULTE,  SKI  WHALE.  395 

of  the  upper  abdomen.  Since  Carte  and  MacAlister  no  general  account  of  the  muscles  in  a 
Mysticete  has  been  given,  and  as  their  dissections  were  performed  two  weeks  after  the  death 
of  their  specimen,  and  their  description  in  many  places  is  extremely  brief,  it  seemed  desirable 
to  use  this  opportunity  for  reexamination  of  this  topic.  As  to  the  abdomen,  Weber  in  his 
important  study  of  the  position  of  the  alimentary  canal  in  the  Cetacea,  has  not  touched  upon 
the  conditions  of  the  lesser  sac,  and  the  general  literature  affords  but  scanty  information  upon  its 
arrangement.  Outside  of  these  two  main  inquiries,  I  have  recorded  briefly  the  results  of  dis- 
section, but  have  refrained  from  detailed  study  of  many  anatomical  structures,  which  in  a  foetus 
of  this  size  were  inconveniently  small  for  dissection,  and  rather  large  for  serial  sections  and 
reconstruction. 

It  has  been  the  purpose  of  this  report  to  record  as  objectively  as  possible  the  organization 
of  this  foetus  of  a  little  studied  species,  and  I  have  confined  myself  rather  strictly  to  my  subject. 
In  particular  I  have  not  attempted  a  collation  or  review  of  the  literature,  but  have  relied 
largely  upon  the  more  recent  studies  in  this  field  for  comparison  and  interpretation,  limiting 
myself  here  again  as  far  as  possible  to  the  works  dealing  particularly  with  the  Balsenopterinse. 

Measurements. 

The  dimensions  of  this  foetus  are  given  in  the  accompanying  table  I  and  their  percentage 
proportions  in  terms  of  the  length  from  the  tip  of  the  rostrum  to  the  notch  in  the  flukes.  While 
the  foetus,  as  has  been  said,  was  curved  in  an  irregular  spiral  it  was  flexible  enough  to  be 
straightened  and  the  measurements  given  were  taken  in  this  position  with  callipers.  In  the 
case  of  a  structure  situated  in  the  dorsal  or  ventral  midline  the  measurement  was  taken  to 
its  transverse  plane  thus  avoiding  obliquity  in  line  of  measurement  and  increase  of  dimensions 
by  following  the  curvature  of  the  surface.  The  dimensions  most  dependent  upon  the  mode  of 
measuring  are  of  course  the  distances  between  dorsal  points  and  in  particular  the  total  length, 
owing  to  the  curvature  of  the  dorsum  and  the  greater  or  less  degree  of  flexion  of  the  head.  In 
this  foetus  the  linear  length  when  the  body  is  straight  is  375  mm.,  but  when  the  curvature  of 
the  dorsum  is  included  it  amounts  to  450  mm. 

Table  I.     Measurements  of  Andrews's  foetus  of  Balcenoptera  borealis. 

mm.  % 

Total  length,  snout  to  notch  of  flukes 375 

Tip  of  snout  to  blow  hole 45  12.0 

Tip  of  snout  to  eye 65  17.3  • 

Tip  of  snout  to  external  auditory  meatus  L.  96  R.  88  Av 92  24 . 5 

Tip  of  snout  to  axilla 110  29.5 

Tip  of  snout  to  umbilicus 185  49.3 

Tip  of  snout  to  anus 257  68.5 

Tip  of  snout  to  hump 233  62.1 

Length  of  hump 16 

Notch  of  flukes  to  umbilicus 180  48.0 

Notch  of  flukes  to  anus 120  32.0 

Notch  of  flukes  to  hump 126  33.6 

Tip  to  tip  of  flukes 81  21 .6 

Anus  to  clitoris 

Anus  to  umbilicus 63  16.8 

Length  of  umbilicus 10  2.6 


396 


SCHULTE,  SEI  WHALE. 


mm.  % 

Depth  of  pedicle  just  anterior  to  flukes 25  6.6 

Depth  of  pedicle  midway  between  flukes  and  anus 36  9.6 

Depth  of  body  at  anus 42  11.2 

Depth  of  body  at  umbilicus 63  16.8 

Depth  of  body  at  shoulder 66  17.6 

Length  of  flipper  tip,  to  anterior  insertion 

Greatest  breadth  of  flipper 14  3.7 

Circumference  at  eye 220  58 . 6 

Circumference  at  shoulder 200  53 . 3 

Circumference  at  umbilicus 173  46 . 1 

Circumference  at  anus 122  32 . 6 

Guldberg  l  has  given  the  dimensions  of  a  larger  foetus  of  Balcenoptera  borealis  taken  in  June 
at  Sorvar  which  are  here  repeated. 

metres. 

Total  length 1 .355 

Length  of  the  head  (from  the  anterior  extremity  of  the  upper  jaw  to  the  meatus  auditorius  externus) ...  0 . 345 

Distance  from  the  anterior  extremity  of  the  lower  jaw  to  the  umbilicus 0 . 685 

Distance  from  middle  of  umbilicus  to  the  median  groove  in  the  caudal  fin 0 . 660 

Length  of  right  anterior  limb • 0 . 185 

Distance  from  anterior  edge  of  the  above  to  anterior  extremity  of  lower  jaw 0 . 415 

Size  of  anterior  limb 0 . 045 

Dorsal  fin,  length  at  base 0.068 

Dorsal  fin,  height 0.050 

Distance  from  dorsal  fin  to  caudal  groove '. 0 . 417 

Distance  from  dorsal  fin  to  extremity  of  lower  jaw 0.875 

Breadth  of  caudal  fin 0.332 

Distance  from  the  anus  to  the  caudal  aperture 0.405 

Distance  from  the  anus  to  the  centre  of  the  umbilicus 0 . 250 

Distance  from  the  anus  to  the  extremity  of  the  lower  jaw 0 . 950 

Collett 2  gives  the  measurements  of  four  still  larger  foetuses  collected  in  the  Varangerfjord 
in  the  month  of  July  as  follows  :— 


Table  II.     Collett' s  measurements  of  four  foetuses  of  B.  borealis. 


Total  length 

Snout  to  angle  of  mouth 

'  Angle  of  mouth  to  flipper 

Length  of  the  flipper 

Width  of  the  flipper 

Snout  to  the  dorsal  fin 

Dorsal  fin  to  end  of  the  tail 

Snout  to  the  navel 

Greatest  height  of  the  body 

Height  at  the  beginning  of  the  dorsal  fin . 

Height  at  the  middle  of  the  tail 

The  least  height  of  the  tail 

Length  of  each  fluke 


16  July 
No.   1,  9 


millim.       millim 


1550 

250 

220 

240 

50 

1030 
520 
760 
240 
170 
140 
100 
200 


18  July 
No.  2,  d" 


19  July 
No.  3,  d" 


1830 

320 

250 

250 

54 

1180 
650 
940 
300 
230 
160 
120 
250 


millim. 

2410 
410 
350 
370 

1550 
860 

1230 
330 
310 
220 


18  July 
No.  4,  c? 


millim. 

2830 
460 
360 
410 

1810 

1020 

1340 

390 

320 

250 

170 

340 


1  Guldberg,  G.  A.     1885.    On  the  existence  of  a  fourth  species  of  the  genus  Batenoptera.     Jour.  Anat.  and  Phys.,  Vol.  XIX,  p.  298. 

2  Collett,  R.     1886.     On  the  external  characters  of  Rudolphi's  rorqual  (Balcenoptera  borealis).     P.  Z.  S.  London,  Part  II,  p.  261. 


SCHULTE,  SEI  WHALE.  397 

For  purposes  of  comparison  the  proportional  dimensions  of  these  foetus  are  given  in  Table  III. 

Table  III.     Comparative  measurements  of  six  foetuses  of  B.  borealis. 


Embryo,  Sex 

R.C. 

Andrews 

9 

Gulberg 

9 

Collett, 
No.  1,  9 

Collett 
No.  2,  rf 

Collett 
No.  3,  o" 

Collett 
No.  4,   o" 

Place  

Aikawa, 
Japan 
JulyS 
375 

% 
24.5 
49.3 
68.5 
62.1 
33.6 
32.0 
18.1 
11.2 
9.5 
21.6 
12.8 
3.7 

Sorvar, 
Norway 
June 
1355 

% 
25.3 
50.6 
70.0 
64.3 
30.8 
29.9 
19.2 

24.5 
13.6 
3.3 

July  16 
1550 

% 

49.0 
66.5 

10.9 
10.3 
25.8 
15.5 
3.2 

Varangers 

July  18 
1830  . 

% 

51.4 
64.5 

12.6 
10.3 
27.3 
13.6 
2.9 

fjord,  No 

July  19 
2410 

% 

51.0 
64.3 

12.3 
9.0 

16.2 

rway 

July  18 
2830 

% 

50.2 
63.9 

11.3 

8.1 
24.1 
14.5 

Date  

Length  in  millimeters  

Snout  to  external  auditory  meatus  .... 
Snout  to  umbilicus  

Snout  to  anus 

Snout  to  hump 

Notch  of  flukes  to  hump 

Notch  of  flukes  to  anus  

Anus  to  centre  of  umbilicus  

Depth  at  anus  

Depth  at  middle  of  pedicle  .           .    . 

Breadth  of  flukes 

Length  of  flipper 

Breadth  of  flipper  

While  neither  Guldberg  nor  Collett  state  their  mode  of  measuring,  the  very  general  corre- 
spondence of  percentages  reckoned  from  their  data  with  the  linear  proportions  of  this  foetus 
makes  it  highly  probable  that  they  too  used  linear  measurements.  The  comparison  of  these 
six  foetuses  shows  no  progressive  change  of  proportion  during  the  period  represented  save  only 
in  the  breadth  of  the  flipper,  which  progressively  diminishes,  being  least  in  the  foetus  of  1830 
mm.,  the  oldest  in  which  this  dimension  is  given,  and  here  a  more  slender  form  is  attained  than 
is  found  in  the  adult,  according  to  Collett's  measurements,1  the  length  bearing  the  ratio  to  the 
breadth  of  1  : 4.7  while  in  the  adult  it  is  as  1  to  3.5  or  1  to  3.6  reckoned  to  the  axilla.  The 
distance  from  rostrum  to  hump  is  in  all  cases  within  the  limits  of  adult  variation  as  given  by 
Collett,  this  dimension  varying  in  five  specimens  between  61  and  68%. 

The  measurements  of  six  fetuses  of  B.  musculus  ( =  physalus)  ranging  in  length  from  4  ft. 
11  in.  to  9  ft.  3  in.  given  by  Burfield  2  makes  possible  a  comparison  with  this  species,  and  I  have 
added  measurement  of  two  foetuses  of  B.  vellifera  and  one  of  B.  sulphurea  collected  by  Mr.  R.  C. 
Andrews  of  the  American  Museum.  I  have  quoted  here  only  the  percentage  table  of  Burfield 
and  have  used  his  points  of  measurement  to  facilitate  comparison. 

This  table  indicates  the  relatively  great  fixity  of  the  position  of  the  anus  in  the  several 
species  at  the  beginning  of  the  last  third  of  the  body;  it  is  in  advance  of  this  in  B.  vellifera  alone 
and  there  only  to  a  very  slight  degree.  Somewhat  more  variable,  but  still  within  narrow  limits 
is  the  position  of  the  umbilicus  just  behind  the  middle  of  the  body,  being  farthest  caudad  in 
B.  physalus  and  B.  vellifera.  B.  borealis  has  the  shortest  rostrum,  the  longest  pectoral  limb 


1  Loe.  at.,  p.  252. 

2  Burfield,  S.  T.,  Belmullet  Whaling  Station.     Report  of  the  Committee  appointed  to  investigate  Biological  Problems  incident  to 
the  Belmullet  Whaling  Station.     Report  of  Bri.  Ass.  Adv.  Sci.,  Dundee,  1912,  p.  145. 


SCHULTE,  SEI  WHALE. 


Table  IV.     Percentage  measurements  of  foetuses  of  Balanoptera  musculus  (=  phy  solus),  borealis, 

vellifera  and  sulphur ea. 


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and  the  hump  of  most  rostral  position,  being  distinctly  in  front  of  the  anus.  It  has  also  the 
widest  flukes.  B.  physalus  has  the  hump  farthest  caudad  and  of  greatest  height  in  the  series, 
and  has  also  the  narrowest  flukes.  In  B.  vellifera  the  flipper  is  broadest,  the  rostrum  longest. 


EXTERNAL  ANATOMY. 

Coloration. —  To  some  extent  the  epidermis  has  desquamated  though  the  precise  limits 
cannot  now  be  determined  accurately.  As  the  pigment  is  epidermal  this  desquamation  has 
reduced  the  colored  area  of  the  foetus,  and  the  following  description  therefore  understates  the 
pigmentation,  which  presumably  was  present  over  the  greater  part  of  the  back.  This,  in  the 
foetus  when  received,  together  with  the  venter  was  a  uniform  light  buff,  except  for  the  lips  of 
the  blow  holes  and  the  ridges  lateral  to  them.  A  narrow  dark  streak  is  present  upon  the  lips. 
On  the  upper  lip  it  is  sharply  limited  orally  by  the  superior  labial  sulcus.  It  extends  forward 
within  a  centimeter  of  the  tip  of  the  snout;  at  the  angle  of  the  mouth  it  turns  inward  beside 
the  ridge  formed  by  the  temporal  muscle,  and  broadening  and  becoming  paler  upon  the  palate 
can  be  followed  to  the  orifice  of  the  pharynx.  A  small  extension  on  each  side  is  directed  rostrad 
beside  the  median  ridge  of  the  palate.  In  the  lower  lip  the  pigmentation  also  stops  abruptly 
at  the  very  minute  inferior  labial  sulcus.  The  streak  becomes  paler  and  broader  towards  the 
angulus  oris  and  fades  out  before  reaching  it.  Rostrad  it  is  prolonged  upon  the  pointed  extrem- 
ity of  the  lips  and  passes  over  their  margin  to  a  slight  degree  upon  their  aboral  surface.  This 
pigmented  area  at  the  symphysis  is  divided  by  two  pale  lines  continuing  the  direction  of  the 
inferior  labial  sulci  into  a  median  triangle  on  the  oral  aspect  of  the  symphysis,  and  an  outer 
V-shaped  area  formed  by  the  union  of  the  labial  streaks.  The  dorsum  of  the  flukes  is  pig- 
mented. They  are  darkest  near  their  caudal  margin  and  become  paler  towards  the  median 
line  and  towards  the  rostral  border,  which  itself  is  unpigmented  as  is  also  the  ridge  of  the  peduncle 
between  the  flukes.  The  posterior  margin  of  the  flipper  and  a  narrow  border  zone  of  its  inner 
surface  are  dark  slate  colored;  the  outer  surface  is  more  extensively  colored  along  the  posterior 
margin  in  the  middle  third  of  its  length,  and  there  is  in  addition  a  narrow  axial  streak  extending 
nearly  to  the  tip.  In  later  foetal  stages  this  type  of  pigmentation  evidently  disappears,  for 
Collett  describes  the  coloration  of  his  specimens,  from  five  to  nine  feet  in  length,  as  being  "homo- 
geneous, a  reddish-brown  on  the  upper  and  under  sides,  without  any  appearance  of  white  on 
the  belly." 

Hairs. —  Eight  very  small  papillae  were  present,  four  on  each  side,  in  a  row  along  the  inferior 
margin  of  the  lower  jaw.  The  most  posterior  is  placed  vertically  below  the  eye,  the  most  ante- 
rior 14  mm.  farther  forward.  The  intervals  between  the  papilla?  increase  in  length  from  behind 
forward  (3,  4  and  6  mm.).  Collett  found  the  hairs  'visible  but  quite  short"  in  his  youngest 
foetus  (155  cm.).  He  does  not  give  their  number  or  arrangement.  In  a  foetus  of  241  cm. 
there  were  seventeen  hairs  on  each  side  in  the  mandibular  region  arranged  in  three  rows,  three 
each  in  the  upper  and  lower  and  eleven  in  the  middle  row.  On  the  upper  jaw  there  were 
seven  hairs  on  each  side  in  a  single  row,  thus  making  a  total  of  thirty-four  hairs  in  this  foetus. 

Outline  of  body. —  The  rostrum  is  moderately  arched,  pronouncedly  decurvate  at  the  tip. 
It  is  separated  from  the  strongly  projecting  brain  case  by  a  shallow  concavity  in  which  are  sit- 
uated the  blow  holes.  From  the  prominence  of  the  cranium  the  dorsal  contour  is  evenly  and 
gently  convex  as  far  as  the  hump,  beyond  which  it  declines  in  a  straight  slope  to  the  beginning 


400 


SCHULTE,  SEI  WHALE. 


Fig.  1.     Lateral  view  of  foetus. 


Fig.  2.     Ventral  view  of  foetus. 


SCHULTE,  SET  WHALE.  401 

of  the  flukes,  where  the  inclination  increases  somewhat.  In  the  whole  length  of  the  upper  ridge 
of  the  peduncle  are  slight  irregular  undulations.  The  integuments  of  the  intermandibular 
region,  throat,  chest,  and  abdomen  nearly  to  the  umbilicus  are  redundant,  baggy  and  very 
freely  movable  on  the  deeper  parts.  There  are  no  furrows.  Just  behind  the  umbilicus  the 
convexity  of  the  belly  ends  and  the  ventral  contour  takes  a  rectilinear  course  to  the  flukes.  The 
vulva  and  anus  occasion  only  a  very  slight  protrusion. 

Head. — -  In  the  convex  rostrum  with  its  downcurved  tip,  the  prominent  eye,  the  great  gape 
of  the  mouth  and  its  prolongation  by  a  surface  furrow  below  and  beyond  the  eye,  the  head  has 
a  remote  and  specious  resemblance  to  that  of  the  sauropside  embryo.  The  rostrum  is  strongly 
arched  transversely  and  presents  a  slight  protuberance  on  each  side  at  the  junction  of  its  first 
and  middle  thirds.  This  is  prolonged  backwards  by  a  low  ridge  in  the  direction  of  the  frontal 
eminence  before  reaching  which  it  merges  in  the  general  relief  of  the  surface.  Above  and  below 
this  ridge  are  concavities.  The  lower  occupies  the  region  between  the  eye  and  the  protuber- 
ance of  the  rostrum;  the  upper,  smaller  and  narrow  is  limited  by  a  median  ridge  which  marks 
the  caudal  half  of  the  rostrum,  bifurcating  as  it  approaches  the  nares  into  two  arms  which  skirt 
the  lateral  margins  of  the  blow-holes.  Between  the  arms  is  a  triangular  slightly  depressed  area, 
which  is  deepened  to  a  sulcus  between  the  blow-holes.  These  are  slightly  curved  with  mesal 
concavity  and  approach  one  another  anteriorly.  Their  length  is  9  mm.  The  distance  between 
their  anterior  extremities  is  2  mm.;  between  their  posterior  extremities  9  mm.  They  are  thus 
inclined  to  the  median  line  at  an  angle  of  68  degrees.  About  each  blow-hole  and  in  the  median 
sulcus  there  is  some  pigmentation  of  the  epidermis. 

Eye. —  The  eye  forms  a  large  prominence  above  the  surface  prolongation  of  the  oral  cavity, 
which  continues  lateral  to  and  beyond  the  temporal  muscle.  Into  this  caudal  extension  of 
the  vestibulum  oris  the  eye  projects  by  its  ventral  convexity.  The  globe  is  covered  by  the  lids 
which  are  fused  together  except  for  a  small  hiatus,  6  mm.  in  length  and  situated  at  the  junction 
of  the  third  and  fourth  vertical  quarters  of  the  ocular  protuberance,  so  that  far  the  larger  seg- 
ment of  the  eye  is  covered  by  the  upper  lid. 

Ear. —  The  external  auditory  meatus  has  a  punctate  orifice  24  mm.  behind  and  9  mm. 
above  the  centre  of  the  eye. 

Lips. —  The  line  of  the  mouth  ascends  with  a  moderate  arch  almost  to  the  eye,  where  its 
direction  changes  curving  downwards  below  the  eye  and  running  out  into  a  surface  furrow  which 
terminates  vertically  beneath  the  ear.  In  its  whole  extent,  save  at  the  decurved  tip  of  the 
rostrum,  the  under  lip  overlaps  the  upper  to  a  slight  degree,  a  condition  the  reverse  of  that  which 
is  usual  in  mammals.  The  tip  of  the  lower  lips  beneath  the  rostrum,  is  everted  and  protrudes 
in  a  rudimentary  spout.  From  this  point  the  margin  of  the  lower  lip,  beginning  as  a  faint  ridge 
rises  into  a  high  thin  flange  beveled  at  the  expense  of  its  oral  surface,  which  upon  reaching  the 
ocular  region  declines  as  rapidly.  Here,  below  the  eye,  the  margin  of  the  lower  lip  is  approached 
by  the  ridge  of  the  temporal  muscle,  directed  from  above  and  behind  rostrad  and  slightly  laterad ; 
the  oral  surface  of  the  lip  becomes  nearly  horizontal,  and  there  is  formed  between  its  margin 
and  the  temporal  ridge  a  concavity,  apposed  to  the  venter  of  the  ocular  protuberance  and  con- 
tinued backward,  lateral  to  the  masseter  muscle,  into  the  surface  furrow  before  mentioned. 
It  is  this  feature,  dependent  upon  the  small  size  of  the  masseter,  the  non-development  of  the 
cheek,  and  the  consequent  rudimentary  condition  of  the  vestibulum  oris,  together  with  the 
absence  of  a  distinct  mandibular  ramus,  which  is  largely  responsible  for  the  curiously  sauropsid 
expression  of  the  cetacean  foetus. 


402  SCHULTE,  SEI  WHALE. 

The  lower  lip  is  marked  sagittally  by  a  minute  furrow.  Beginning  as  an  unpigmented  line 
at  the  symphysis  it  runs  in  the  intermediate  region  rather  nearer  the  base  than  the  margin  of 
the  lip,  here  forming  the  oral  limit  of  the  pigment-streak.  On  reaching  the  temporal  ridge  the 
furrow  turns  on  its  mesal  surface,  eventually  ascending  slightly  to  be  lost  in  a  depression  which 
corresponds  to  the  orbital  triangle  of  other  mammals.  Obviously  in  the  post-temporal  segment 
the  furrow  has  ceased  to  have  the  significance  of  a  labial  or  dento-labial  sulcus,  and  it  is  evident 
that  here  an  independent  element  has  become  secondarily  continuous  with  that  furrow. 

The  labial  sulci  diverge  for  about  three  fourths  of  their  length  and  then  converge  more 
rapidly.  They  thus  describe  curves  of  lateral  convexity  and  are  farthest  apart  immediately 
in  front  of  the  eyes.  In  the  caudal  segment  of  their  course  they  sweep  mesad  to  the  ridge  of  the 
temporal  muscle  and  end  in  a  fossa  of  the  roof  of  the  mouth  mesal  to  this  muscle  and  ventral 
to  the  orbit  (orbital  triangle).  Lateral  to  the  dental  sulci  are  the  low  ridges  which  form  the 
upper  lips.  These  broaden  caudad  and  in  the  ocular  region  merge  with  the  convexities  which 
correspond  to  the  under-surface  of  the  eye,  and  form  the  roof  or  upper  boundary  of  the  subocular 
extension  of  the  oral  cavity. 

Naso-vomerine  organ. —  At  the  tip  of  the  rostrum,  between  the  extremities  of  the  dento- 
labial  sulci  is  situated  a  small  tripartite  elevation.  It  is  separated  from  the  surface  of  the  ros- 
trum by  the  terminal  portions  of  these  sulci,  and  from  the  palate  by  a  small  transverse  furrow 

continuous  with  the  dento-labial.  In  the  median  line,  the  middle 
lobe  of  the  elevation  forms  a  bridge  between  the  rostral  surface  and 
the  palate  interrupting  the  sulci,  or  at  least  reducing  their  depth. 
This  portion  is  triangular  with  the  base  caudad.  To  its  sides  are 
attached  the  lateral  lobes,  which  are  reniform,  with  their  concavi- 
ties mesad.  Lateral  to  them  the  dento-labial  sulci  are  deepened  to 
little  blind  pits.  They  thus  are  very  similar  to  the  structures 
Fig.  3.  Naso-vomcrine  organ,  described  and  figured  by  Weber,1  and  by  him  interpreted  as  the 

rudiments  of  Steno's  ducts.      In   the   slightly  older  foetuses  of 

Balcenoptera  and  of  Megaptera,  which  I  have  examined,  the  bounding  sulci  diminish,  the  lateral 
lobes  merge  into  the  general  relief  of  the  rostrum,  and  the  little  pits  deepen  somewhat,  changes 
which  seem  to  lead  up  to  the  conditions  described  by  Lillie.2 

The  flipper. —  The  flipper  attains  its  greatest  thickness  close  to  the  preaxial  border  and 
maintains  it  for  about  two  thirds  of  its  breadth,  the  postaxial  third  being  reduced  to  a  thin 
plate.  It  is  slightly  narrowed  at  its  emersion  from  the  integumentary  covering  of  the  trunk, 
immediately  distad  of  the  olecranon.  From  this  point  it  gradually  expands  for  two  thirds  of 
its  length  and  then  more  rapidly  tapers  to  its  pointed  extremity  chiefly  at  the  expense  of  its 
postaxial  portion.  The  preaxial  border  is  not  quite  straight  but  has  an  anterior  convexity  in 
its  third  quarter,  beyond  which  the  outline  has  three  slight  projections  corresponding  to  the 
interphalangeal  joints  of  digit  II.  The  postaxial  border  is  convex  caudad  in  its  proximal  two 
thirds.  Its  distal  third  is  rectilinear  save  for  a  shallow  concavity  close  to  the  extremity,  which 
gives  the  tip  of  the  flipper  a  faintly  hooked  contour. 


1  Weber,  M.     Studien  ilber  Saugethiere.     Leipzig,  1885,  page  145  and  pi.  iv   figs.  22-24.     Cf.  also  Kuckenthal,  Denkschr  Merl.- 
Xat.  Gesells.  Jena,  1889. 

2  Lillie,  D.  G.     Observations  on  the  Anatomy  and  General  Biology  of  some  members  of  the  larger  Cetacea.     P.  Z.  S.,  1910.  p.  784 
and  text  fig.  75.     Seo  also  Burfield,  S.  T.     Belmullet  Whaling  Station.     Rep.  Bri.  Ass.  Adv.  Sci.,  Dundee,  1912. 


SCHULTE,  SEI  WHALE.  403 

The  hump. —  The  hump  is  triangular  with  rounded  apex.  Its  longest  side  is  attached, 
the  intermediate  is  rostral,  the  shortest  caudal.  It  is  not  falciform.  Its  caudal  end  is  nearly 
opposite  the  vulva,  distinctly  in  front  of  the  anus.  Guldberg  states  that  the  posterior 
extremity  is  opposite  the  anus,  but  his  measurements  (vide  ante)  indicate  that  it  is  somewhat  in 
advance  of  the  latter. 

The  flukes. —  The  flukes  are  strongly  rolled  on  themselves  ventrad.  The  ridges  of  the 
pedicle  are  prolonged  between  them  to  the  notch,  which  is  deep  and  narrow. 

The  vulva. —  The  vulva  presents  a  prominent  conical  clitoris  which  overhangs  the  vestibule. 
This  is  bounded  at  the  sides  by  low  ridges,  the  labia  majora.  Caudad  the  vestibule  rises  gradu- 
ally to  the  level  of  the  perineum,  here  presenting  three  short  furrows,  a  median  sagittal,  and  two 
lateral  diverging  with  slight  mesal  convexity.  On  either  side  are  the  slits  of  the  mammary 
pockets  each  about  2  mm.  in  length.  There  was  no  asymmetry  of  the  external  genitalia. 

The  anus. —  The  anus  is  slightly  elongated  sagittally  separated  by  a  convexity  from  the 
vulva.  The  region  about  it  is  but  slightly  elevated  above  the  general  relief  of  the  adjacent 
surface. 

MYOLOGY. 
(Plates  LXIII-LXVin.) 

The  chief  source  for  the  myology  of  the  Mystacoceti  is  the  study  by  Carte  and  MacAlister ! 
of  Balcenoptera  rostrata  ( =  acuto-rostrata)  published  in  1869.  Since  that  time  the  musculature 
of  the  suborder  has  not  again  been  investigated  as  a  whole,  and  the  list  of  authors  dealing  with 
it  at  all  is  surprisingly  small  in  comparison  with  those  that  have  directed  their  attention  to  the 
toothed  whales.  No  doubt  the  accessibility  and  the  smaller  size  of  many  members  of  the  latter 
suborder  is  largely  accountable  for  this.  As  it  is,  Perrin  2  has  partially  reexamined  B.  acuto- 
rostrata,  and  has  reported  his  findings  briefly  in  the  form  of  addenda  et  corrigenda  to  the  work 
of  Carte  and  MacAlister.  Beauregard  3  has  described  in  much  detail  the  masseter  and  temporal 
muscle  of  B.  Sibaldii  (  —  musculus)  and  B.  musculus  (  —  physalus)  and  there  are  further  the  impor- 
tant studies  of  Weber 4  upon  the  ocular  muscles  and  of  Dubois 5  upon  those  of  the  larynx.  The 
fine  work  of  Struthers  fi  upon  the  intrinsic  muscles  of  the  flipper,  and  upon  those  of  the  pelvis 
about  exhausts  the  list.  In  these  circumstances  I  have  found  it  necessary  to  refer  to  the  more 
abundant  literature  of  the  Odontoceti  on  many  occasions,  but  it  is  needless  to  say  I  have  at- 
tempted no  general  consideration  of  the  comparative  myology  of  the  two  suborders,  nor  do  I 
conceive  that  this  could  profitably  be  undertaken  on  the  basis  of  our  present  scanty  knowledge 
of  this  subject  in  the  Mystacoceti. 


1  Carte,  A.,  and  MacAlistor,  A.     On  the  anatomy  of  Balwnoplera  rostrata.     Phil.  Trans.  Roy.  Soc.  London,  Vol.  158,  p.  201 . 

2  Perrin,  J.  B.     Notes  on  the  anatomy  of  Balomoptera  roslrata.     P.  Z.  S.,  1870,  p.  805. 

3  Beauregard,  H.     Etude  de  1'articulation  temporo-maxillaire  chez  les  Bala>nopte>es.     Jour,  de  1'Anat.  et  do  la  Phys.,  An.  XVIII, 
1882,  p.  16. 

4  Weber,  Max.    Studien  iiber  Siiugethiere,  Jena,  1886,   p.  119. 

5  Dubois,  E.     Idem.,  p.  93. 

6  Struthers,  J.     On  some  points  in  the  anatomy  of  a  great  finwhale  (Balcenoptera  musculus).     Jour.  Anat.  and  Phys.,  Vol.  VI,  1871, 
p.  107.     Account  of  rudimentary  finger  muscles  found  in  the  Greenland  right  whale  (Balama,  mysticelus).     Jour.  Anat.  and  Phys..  Vol. 
XII,  1878,  p.  217.     On  the  bones,  articulations,  and  muscles  of  the  rudimentary  hind  limb  of  the  Greenland  right  whale  (Balcena  mysti- 
celus).   Jour.  Anat.  and  Phys.,  Vol.  XV,  1881,  p.  141  and  p.  301.     Nature,  Vol.  IV,  1884,  p.  342,  contains  in  the  proceedings  of  tho 
Biol.  Sect.  A.  A.  A.  a  paragraph  to  the  effect  that  rudimentary  finger  muscles  are  present  in  Megaptrra  lonf/innnm . 


404  SCHULTE,  SEI  WHALE. 

Panniculus  carnosus  —  The  cutaneous  musculature  is  highly  developed,  forming  an  unin- 
terrupted layer  upon  the  sides  and  venter  of  the  trunk  from  the  occiput  to  the  beginning  of 
the  pedicle  and  being  continued  beyond  this  point  by  a  firm  aponeurosis  which  completely  invests 
the  tail.  It  adheres  firmly  to  the  derma,  beneath  which  little  or  no  fat  has  as  yet  formed,  but 
is  in  general  separated  from  underlying  structures  by  a  moderate  quantity  of  loose  areolar  tissue. 
In  the  region  of  the  ventral  pouch  however,  it  is  intimately  conjoined  with  the  deeper  layers 
by  firm  connective  tissue,  and  the  whole  complex  is  separated  from  underlying  structures  by  a 
great  area  of  very  loose  tissue,  the  cavum  ventrale. 

As  a  whole  the  panniculus  falls  into  two  divisions,  one  dorsal  and  the  other  ventral,  the 
two  united  by  a  lateral  raphe  as  far  cephalad  as  the  flipper,  in  front  of  which  they  overlap,  the 
fasciculi  of  the  dorsal  division  passing  superficially  to  those  of  the  ventral.  This  raphe  extends 
from  the  axilla  to  beyond  the  vent,  inclining  toward  the  mid  ventral  line  as  it  passes  caudad. 
Its  axillary  extremity  is  attached  to  the  humerus  in  union  with  the  insertions  of  the  latissimus 
dorsi  and  pectoralis  muscles,  which  insert  also  into  the  proximal  portion  of  the  raphe.  At  its 
beginning  linear  and  permitting  a  slight  degree  of  interdigitation  on  the  part  of  the  inserting 
fasciculi,  it  gradually  widens  into  a  broad  band  which  merges  behind  the  vent  into  the  apo- 
neurosis of  the  pedicle. 

The  dorsal  division  arises  from  a  broad  aponeurosis  which  covers  the  dorsal  muscles  and 
in  the  midline  is  connected  to  the  spines  of  the  vertebrae  by  a  vertical  lamella  which  intervenes 
between  the  muscle  masses  of  the  two  sides.  Its  fasciculi  are  directed  ventrad  and  cephalad, 
inserting  into  the  lateral  raphe,  the  dorsal  aspect  of  the  aponeurosis  of  the  flipper,  and  in 
front  of  this  passing  as  a  thin  sheet  of  scattered  fasciculi  ventrad  across  the  side  of  the  neck  to 
the  intermandibular  region,  where  they  sweep  rostrad  almost  to  the  symphysis.  Some  of  them 
reach  the  midline  and  there  interdigitate  with  the  bundles  of  their  antimere;  the  majority  do 
not  extend  so  far  but  find  scattered  insertions  into  the  derma  along  the  side  of  the  ventral  pouch: 
The  dorsal  division  extends  sagittally  from  the  occiput  to  near  the  middle  of  the  pedicle;  here 
it  rapidly  narrows,  the  bundles  arising  at  an  increasing  distance  from  the  dorsal  midline  but 
maintaining  their  regular  arrangement  and  constituting  a  continuous  sheet  throughout. 

The  ventral  division  arises  from  the  ventral  midline,  its  fasciculi  showing  a  tendency  to 
interdigitate  with  those  of  the  opposite  side.  To  some  extent  they  are  separated  by  a  line  of 
fibrous  tissue  which  blends  with  their  deep  epimysium  but  is  not  firmly  connected  with  the 
linea  alba.  At  the  umbilicus  the  muscles  of  the  two  sides  separate  to  give  passage  to  the  cord. 
Here  there  is  a  considerable  increase  in  the  quantity  of  connective  tissue,  both  of  the  pannicular 
layer  and  more  especially  in  the  linea  alba.  The  panniculus  has  a  well  defined  edge  and  none  of 
its  fasciculi  are  prolonged  upon  the  cord.  Sagittally  the  ventral  division  extends  from  the  sym- 
physis mandibularum  a  short  distance  beyond  the  vent.  Its  fasciculi  have  a  rostro-lateral  or 
dorsal  direction  and  form  a  continuous  sheet.  This  is  very  thin  in  the  intermandibular  region 
and  very  firmly  united  with  the  overlying  scattered  fasciculi  of  the  dorsal  division  and  on  its 
deep  surface  with  the  mylohyoid,  from  both  of  which  it  is  distinguished  by  the  direction  of  its 
bundles.  These  lajrers  together  with  a  deeper  stratum  of  longitudinal  direction  constitute 
the  muscular  wall  of  the  ventral  pouch  and  form  a  well  defined  complex,  which  is  only  with  great 
difficulty  resolved  by  dissection  into  its  component  elements.  The  fasciculi  of  the  ventral 
panniculus  can  be  followed  in  part  to  the  lips  and  some  of  them  reach  the  mandible  in  front 
of  the  insertion  of  the  masseter,  but  many  of  them  terminate  within  the  intermandibular  region 


PLATE  XLIII. 


PLATE  XLIII. 

Balcmoptera  borealis. 

Fig.  1.     Superficial  dissection  exposing  panniculus  carnosus.     f  natural  size. 

Fig.  2.    Musculature  of  ventral  pouch.    Ventral  division  of  panniculus  has  been  reflected,     f  natural  size. 

1.  Ventral  division  of  panniculus.  5.     Longitudinal  muscle  of  ventral  pouch. 

2.  Dorsal  division  of  panniculus.  6.     M.  sternomandibularis. 
3     Lateral  raph6.  7.     M.  pectoralis. 

4.     M.  mylohyoideus. 


Memoirs  Am.  Mus.  Nat.  Hist. 


X.  S.,  Vol.  I,  Plate  XLIII. 


02 

I 

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.s>    « 

pL|  £3 


SCHULTE,  SKI  WHALE.  4o;, 

on  the  surface  of  the  mylohyoid  muscle,  presumably  by  means  of  a  fibrous  inscription  but  the 
precise  details  of  their  insertion  I  could  not  determine  in  this  foetus.  Carte  and  MacAlister 
describe  a  peculiar  fibrous  structure  in  connection  with  the  mylohyoid  and  as  their  description 
is  somewhat  obscure  to  me  I  give  it  literally:  "Occupying  the  inferior  or  superficial  part  of 
the  interspace  between  the  rami  of  the  lower  jaw  in  the  anterior  part  of  the  middle  line  was 
a  condensed  fibrous  expansion,  which  extended  forwards  as  far. as  the  symphysis,  and  was  bifur- 
cated posteriorly  at  the  middle  point  of  the  lower  jaw,  giving  attachment  to  the  following  muscle 
(mylohyoid)."  In  a  foetus  of  Megaptera  versabilis  of  Mr.  Andrews's  collection  which  I  dissected 
with  a  view  of  gaining  a  better  understanding  of  the  musculature  of  the  ventral  pouch,  a  fibrous 
structure  somewhat  resembling  the  foregoing  was  present.  In  the  midline  immediately  behind 
the  symphysis  mandibularum  a  sagittal  ridge  projects  from  the  surface  of  the  skin  with  a  length 
of  something  over  1.5  cm.  This  is  caused  by  a  local  thickening  of  the  derma.  Caudad  its  sur- 
face relief  ends  abruptly,  but  on  dissection  it  is  found  to  be  prolonged  by  two  fibrous  strands 
on  the  surface  of  the  mylohyoid,  parallel  to  and  at  a  distance  of  about  1  cm.  from  the  lower 
margins  of  the  mandibles,  extending  for  somewhat  more  than  a  third  of  the  length  of  the  jaw. 
The  whole  tendinous  structure  has  then  the  shape  of  a  Y,  the  stem  at  the  symphysis  and  the 
arms  stretching  caudad  roughly  parallel  to  the  mandibular  rami.  It  thus  would  have  a  general 
resemblance  to  the  structure  described  by  Carte  and  MacAlister,  if  they  could  be  understood  as 
meaning  that  it  terminates,  not  bifurcates,  opposite  the  middle  of  the  ramus.  That  this  was 
their  intention  is,  I  think,  probable  from  their  description  of  the  mylohyoid  muscle,  of  which 
only  the  anterior  portion  is  given  as  arising  from  the  fibrous  structure,  the  remainder  having  the 
usual  origin  from  the  mandible.  It  remains  to  question  whether  this  fibrous  structure  actually 
replaces  the  mandible  in  part  as  the  origin  of  the  mylohyoid  or  serves  some  other  purpose.  In 
the  fcetus  of  B.  borealis  I  thought  I  could  follow  the  mylohyoid  to  the  jaw  in  its  whole  length. 
In  that  of  Megaptera  this  was  certainly  the  case,  and  the  fibrous  arcade  received  only  fasciculi 
of  the  ventral  panniculus,  which  were  thus  attached  to  the  ectal  surface  of  the  mylohyoid  by  a 
tendinous  inscription.  The  contraction  of  this  part  of  the  panniculus  would  therefore  seem  to 
serve  to  deepen  the  oral  cavity  by  pulling  down  the  floor  of  the  alveolingual  region.  Not  all 
of  the  fasciculi  of  the  ventral  panniculus  had  this  insertion,  however,  for  some  were  prolonged 
beyond  the  inscription  and  passing  over  the  border  of  the  mandible  were  lost  in  the  substance 
of  the  lower  lip. 

Caudal  to  the  intermandibular  region  the  ventral-  panniculus  ascends  upon  the  sterno- 
mandibularis  under  cover  of  the  overlying  fasciculi  of  the  dorsal  panniculus.  Its  fasciculi  are 
inserted  into  the  caudal  portion  of  the  lower  lip  and  into  the  derma  of  the  subocular  furrow 
that  prolongs  the  vestible,  and  more  caudally  still  reach  the  malar  bone  and  the  zygomatic 
process  of  the  squamosal.  In  the  pectoral  region  they  cross  the  axilla  to  reach  the  ventral 
aponeurosis  of  the  flipper,  here  joining  the  pectoralis,  and  caudal  to  the  flipper  they  reach  the 
lateral  raphe  which  unites  them  to  the  dorsal  division. 

The  innervation  of  the  panniculus  carnosus  falls  into  two  districts.  Behind  and  at  the 
shoulder  it  is  supplied  by  a  pannicular  or  lateral  thoracic  nerve,  the  lateral  cutaneous  of  English 
authors,1  which  runs  caudad  beneath  the  lateral  raphe  distributing  branches  to  both  the  dorsal 


1  Wilson,  J.  T.  The  innorvation  of  axillary  muscular  arches  in  man,  with  remarks  on  their  homology.  Jour.  Anat.  and  Phys., 
Vol.  XXII,  1888.  Further  observations  on  the  innervation  of  axillary  muscles  in  man.  Jour.  Anat.  and  Phys.,  Vol.  XXIV,  1889. 
Birmingham,  A/  Homology  and  innervation  of  the  Achselbogen  and  Pectoralis  quartus  and  the  nature  of  the  lateral  cutaneous  nerve 
of  the  thorax.  Jour.  Anat.  and  Phys.,  Vol.  XXIII,  1889. 


406  SCHULTE,  SEI  WHALE. 

and  ventral  divisions.  In  the  neck  and  intermandibular  regions  the  nerve  supply  is  derived 
from  several  branches  of  the  facial  which  have  a  general  ventro-rostral  direction  on  the  deep 
surface  of  the  muscle.  One  of  larger  size  emerging  at  the  anterior  border  of  the  depressor  man- 
dibula?  crosses  the  masseter  and  is  continued  rostrad  parallel  to  the  lower  margin  of  the  mandible 
in  a  position  which  might  lead  to  its  confusion  with  the  mylohyoid  nerve. 

This  description  of  the  panniculus  differs  materially  from  the  observations  of  Carte  and 
MacAlister  upon  a  specimen  of  Balcenoptera  acuto-rostrata.  They  report  a  platysma  myoides 
which  "could  be  seen  only  in  the  median  line,"  and  found  that  the  "portion  of  the  neck  external 
to  the  inner  margin  of  the  sternomastoid  had  no  superficial  muscular  investment."  On  the 
other  hand  Stannius  :  describes  in  Phoccena  a  panniculus  with  dorsal  and  ventral  divisions  sepa- 
rated by  a  lateral  raphe  and  except  in  the  intermandibular  region  and  in  its  more  intimate  rela- 
tions to  the  pectoralis  closely  resembling  the  superficial  musculature  of  this  foetus  of  B.  borealis. 
A  panniculus  of  the  Phoccena  type  is  also  present  in  foetuses  of  Tursiops  truncatus,  and  Murie  2 
has  described  one  of  extensive  but  modified  development  in  Globiocephalus.  The  conclusion 
would  therefore  seem  warranted  that  the  panniculus  is  extensive  and  highly  developed  in  the 
Cetacea  (Leche),3  and  that  Balcenoptera  is  not  an  exception  to  the  rule,  but  in  correlation  with 
its  throat  furrows  possess  this  muscle  in  a  highly  developed  form.  The  persistence  of  the  sub- 
cutaneous musculature  in  these  well-nigh  hairless  forms  can  not  wholly  be  ascribed  to  its  inser- 
tion upon  the  flipper,  but  would  seem  to  stand  in  relation  to  the  maintenance  of  pressure  upon 
the  contents  of  the  abdominal  and  thoracic  cavities  as  the  animal  rises  to  the  surface;  in  accord 
with  this  view  is  the  confinement  of  muscular  fasciculi  to  the  ventral  and  lateral  regions  of  the 
trunk  and  their  replacement  by  aponeurosis  over  the  massive  dorsal  muscles  and  upon  the 
pedicle. 

Cavum  ventrale. —  This  is  an  extensive  area  of  very  delicate  areolar  tissue  which  gives  way 
almost  without  dissection.  It  reaches  from  the  intermandibular  region  to  within  a  short  dis- 
tance of  the  umbilicus.  Ventrally  it  is  closed  by  the  muscle  complex  of  the  ventral  pouch, 
which  is  reinforced  on  the  side  turned  towards  the  cavum  by  a  strong  and  moderately  thick 
aponeurosis.  At  the  sides  its  boundaries  are  formed  by  the  sternomandibularis  and  their  invest- 
ing fascia.  The  dorsal  limit  is  given  by  a  dense  and  thick  aponeurosis  which  covers  the  supra- 
and  infrahyoid  muscles  and  from  its  position  corresponds  to  the  usual  deep  fascia  of  the  neck. 
Over  the  pectoralis  and  external  oblique  it  becomes  thinner,  and  as  it  approaches  the  umbilicus 
it  fuses  with  the  aponeurosis  of  the  pouch  muscles  and  so  closes  the  cavum  caudally.  Rostrad 
the  space  does  not  extend  quite  to  the  symphysis  and  bodies  of  the  mandibles,  but  is  brought  to 
an  end  inside  their  arch  by  the  approximation  of  the  pouch  muscles  to  the  genioglossus. 

The  musculature  of  the  ventral  pouch. —  In  addition  to  the  panniculus  this  comprises  the 
mylohyoid  and  a  longitudinal  stratum  of  cervico-hypoglossal  innervation.  The  muscles  are 
in  the  form  of  thin  sheets  very  firmly  united  by  connective  tissue.  Their  general  arrangement 
in  cross  section  is  shown  in  the  accompanying  photomicrograph  (Text-fig.  4).  Ectally  are 
scattered  bundles  of  the  dorsal  panniculus,  obviously  here  equivalent  to  the  platysma  myoides. 
These  are  followed  by  the  more  abundant  fasciculi  of  the  ventral  division,  cut  nearly  at  right 
angles.  The  mylohyoid  forms  the  third  layer  and  is  very  tenuous.  Entally  are  the  larger 
bundles  of  the  longitudinal  layer  which  is  thicker  than  any  of  the  others. 

1  Beschreibung  der  Muskeln  des  Ttimmlers  (Delphinus  phoccena).     Miiller's  Arch.,  Jahrg.  1849. 

2  On  the  Organization  of  the  Caaing  Whale,  Globiocephalus  melas.    Trans.  Zool.  Soc.  London,  Vol.  VIII,  1874. 

3  Braun's  Klassen  und  Ordungen  des  Thier-Reichs;  Saugethiere,  Bd.  I,  p.  669. 


SCHULTE,  SEI  WHALE.  407 

The  mylohyoid  arises  in  the  usual  manner  from  the  oral  surface  of  the  mandible  along  a 
line  which  ascends  somewhat  on  the  bone  in  the  direction  of  the  ramus.  Its  fasciculi  are  directed 
to  the  median  line  with  an  inclination  rostrad  to  unite  with  their 
antimere  by  means  of  a  poorly  developed  raphe  which  permits 
of  some  interdigitation,  the  two  halves  of  the  muscle  being  dis- 
tinguished more  by  the  inclination  of  their  bundles  than  by  the 
amount  of  connective  tissue  interposed.  The  innervation  is  by 
the  usual  mylohyoid  branches  of  the  inferior  maxillary  nerve, 
which  also  supplies  the  anterior  belly  of  the  digastric  and  is  placed 
upon  the  ectal  surface  of  the  muscle  close  to  the  mandible. 
There  was  no  attachment  either  of  the  raphe  or  of  the  mylohyoid 
to  the  body  of  the  hyoid,  from  which  the  muscle  is  separated  by 
the  longitudinal  layer  already  referred  to  as  the  deepest  stratum 
of  the  pouch.  In  the  post  mortem  distension  of  the  ventral 
pouch  by  gases,  the  caudal  border  of  the  mylohyoid  produces  a 
transverse  furrow  sometimes  of  considerable  depth  as  is  shown  * 

in  Turner's  illustration,1  and  particularly  well  in  Andrews'  photo- 
graph (unpublished).  Fig.4-     Photomicrograph  of  coronal 

The  longitudinal  muscle  of  the  pouch  extends  from  its  caudal        secti°n  of  ^  mfc!es. of  the, ventral 

pouch.     1,  Dorsal  division  of  panni- 

limit  in  front  of  the  umbilicus  to  the  mandibular  arch.     It  arises        cuius  camosus  (c/.  PI.  XLIII,  fig.  i). 

i  ,i  i     i     •,    •       r       i         •  j  2,  Ventral  division  of  same.     3,  Mvlo- 

in  successive  sheets,  so  that  as  a  whole  it  is  of  a  laminated  struc-        hyoid    4>  ^^^1  stratum.  ' 
ture,  from  the  deep  surface  of  the  intermuscular  septum  between 

it  and  the  ventral  panniculus.  The  layers  of  thoracic  origin  are  superficial  to  those  beginning 
farther  caudad.  On  reaching  the  mylohyoid  it  passes  upon  its  dorsal  or  oral  surface  and  is 
attached  to  the  mandibles  immediately  dorsal  to  the  insertion  of  that  muscle.  As  it  approaches 
the  jaw  it  becomes  firmly  united  with  the  genioglossus  to  an  extent  approximately  corresponding 
to  the  floor  of  the  alveolingual  region,  in  this  detail  differing  from  conditions  observed  in 
Megaptera,  where  it  is  easily  separable  from  that  muscle.  The  union  in  Balcenoptera  is  by  con- 
nective tissue  only;  I  could  find  no  exchange  of  fasciculi.  As  the  longitudinal  layer  passes  the 
sternomandibularis  in  the  neck  it  receives  in  its  lateral  portion  a  contribution  of  bundles  from 
that  muscle,  a  condition  which  is  more  marked  in  Megaptera.  The  relation  of  the  two  muscles 
is  further  shown  by  their  innervation  from  the  hypoglossal  after  it  has  received  the  communica- 
tion of  the  cervical  nerves,  the  longitudinal  muscle  receiving  a  large  branch  which  ramifies  on  its 
ental  surface. 

Carte  and  MacAlister  describe  a  mylohyoid  of  loose  structure,  "composed  of  fine  muscular 
fibres  and  areolar  tissue  permeated  by  numerous  blood  vessels";  the  fibres  in  the  midline  inter- 
lace with  those  of  its  fellow;  no  mention  is  made  of  an  origin  from  the  body  of  the  hyoid,  which 
as  their  description  is  detailed,  it  may  be  taken  that  the  muscle  did  not  possess.  In  the  matter 
of  structure,  the  muscles  of  this  region,  though  thin,  were  far  more  compact  in  this  foetus  than 
in  their  specimen.  As  in  the  fcetus  of  Megaptera  the  fasciculi  were  less  coherent  and  in  their 
interstices  delicate  areolar  tissue  was  more  abundant,  it  would  seem  that  an  increasing  invasion 


1  Turner,  Wm.     An  account  of  the  Great  Firmer  Whale  (Balcenoptera  Sibaldii)  stranded  at  Longniddry.     Part  I.     The  Soft  Parts. 
Trans.  Roy.  Soc.  Edinburgh,  Vol.  XXVI,  1872,  plate  v,  fig.  1. 


KIN  SCHULTE,  SEI  WHALE. 

of  the  muscles  by  connective  tissue  takes  place  during  foetal  life.     Carte  and  MacAlister's 
description  concludes  as  follows: 

"The  inferior  or  posterior  fibres  of  this  muscle  ran  downwards  as  far  as  the  lower  part  of 
the  pouch,  and  some  of  them  were  traceable  backwards  in  the  median  line,  forming  a  sort  of 
subcutaneous  muscular  expansion  on  the  anterior  surface  of  the  abdomen;  this,  however,  did 
not  expand  laterally  in  the  cervical  region,  and  hence  that  part  of  the  neck  external  to  the  inner 
margin  of  the  sterno-mastoid  muscle  had  no  superficial  muscular  investment." 

They  would  thus  seem  to  have  considered  the  longitudinal  layer  an  extension  of  the  mylo- 
hyoid,  which  is  probably  to  be  attributed  to  the  "dartoid  character"  of  the  muscle  in  their 
specimen  and  its  infiltration  with  fat  making  an  exact  discrimination  impossible.  The  nerve 
supply  would  have  cleared  up  the  condition,  but  this  they  do  not  seem  to  have  ascertained. 

The  redundancy  of  the  musculo-cutaneous  complex  of  the  ventral  pouch  in  reference  to 
the  deeper  structures  is  a  striking  peculiarity  of  this  fcetus  as  contrasted  with  those  of  the 
toothed  whales.  While  as  yet  no  furrows  have  appeared,  we  are  evidently  dealing  with  their 
antecedent  developmental  condition. 

It  is  to  be  noted  that  the  extent  of  the  pouch  far  exceeds  the  limits  of  the  intermandibular 
region  and  is  patently  in  excess  of  the  demands  for  space  incident  to  the  distensibility  of  the 
oral  cavity,  so  that  Kuckenthal's  reference  of  the  throat  furrows  to  this  cause  alone  would  not 
seem  to  afford  an  adequate  explanation  of  their  presence  on  the  thorax  and  abdomen.  Andrews  ! 
has  suggested  that  originating  in  the  intermandibular  region  their  caudal  extension  has  taken 
place  in  correlation  with  the  increased  expansion  of  the  thorax  incident  to  the  large  size  of  the 
lungs  and  the  reduction  of  the  sternal  fixation  of  the  ribs  in  the  Balsenopterinse,  an  explana- 
tion which  has  the  advantage  of  including  a  larger  number  of  facts  and  which  accords  with 
the  structure  and  extent  of  the  integumentary  complex.  The  difficulty  that  meets  us  here  is 
to  find  grounds  for  attributing  to  the  ribs  under  the  action  of  the  inspiratory  muscles  in  life 
an  excursion  of  such  degree  as  to  require  and  utilize  a  redundancy  of  the  integuments.  Mliller  2 
has  thought  that  the  increased  freedom  of  the  ribs  in  Mystacoceti  stood  in  relation  to  a  lessened 
degree  of  diaphragmatic  respiration  as  contrasted  with  the  Odontoceti.  In  favor  of  this  he 
finds  the  greater  size  of  the  inspiratory  muscles  in  the  former  and  the  diminishing  develop- 
ment of  the  diaphragm  in  their  older  foetuses,  in  one  of  which  he  found  a  centrum  tendineum. 
But  granted  that  such  a  distinction  can  be  established  between  the  two  suborders,  it  is  still 
to  be  shown  that  it  can  become  quantitatively  so  great  in  the  rorquals  as  to  require  an  ampli- 
fication of  the  integuments,  and  it  is  also  a  question  whether  in  them  the  type  of  respiration  is 
not  still  predominantly  abdominal  even  though  it  be  so  in  less  degree  than  in  the  toothed  whales. 
Hasse 3  has  presented  much  evidence  to  show  that  the  direction  of  the  respiratory  movements 
of  the  several  parts  of  the  thorax  accords  with  the  direction  of  the  corresponding  bronchi,  and 
that  the  degree  of  the  movement  is  proportional  to  the  diameter  of  the  bronchus.  With  this 
in  mind  the  pattern  of  the  bronchial  tree  of  B.  musculus,  as  given  by  Muller  (cf.  op.  cit.  Fig.  39) 
would  seem  by  the  inclination  of  its  secondary  branches  to  indicate  an  abdominal  type  of  respira- 


1  Andrews,  R.  C.    Monographs  of  the  Pacific  Cetacca,  I.     The  California  Gray  Whale  (Rhachianectes  glaucus  Cope).     Mem   Am 
Mus.  Nat.  Hist.,  N.  S.,  Vol.  I,  Ft.  V.     New  York,  1914. 

8  Muller,  O.     Untersuchungen  tiber  die  Veranderungen,  welche  die  Respirationsorgane  der  Saugetiere  durch  Anpassung  an  das 
Leben  in  Wasscr  erlitten  haben.     Jenaish.  Zeitsch.  f.  Naturwiss.,  Bd.  32,  1898. 

3  Hasse,  C.     Die  Forraen  des  menschlichen  Korpers  und  die  Formandcrungen  dcsselben  bei  der  Atmung.     Jena,  1888-1890.     Bi>- 
merkungen  iiber  den  Bau  der  Lungen  und  iiber  die  Form  des  Bruskorbes  bei  dem  Menschen  und  bei  den  Saugetieren      Arch   f    \int 
und  Phys.,  1893. 


SCHULTE,  SKI  WHALE.  409 

tion.  Yet  in  strictness  as  this  is  a  foetal  lung,  this  could  be  considered  indicative  only  of  the 
primitive  type  of  breathing  of  the  species  and  not  absolutely  of  its  adult  condition  which  might 
be  adaptively  modified.  What  the  adult  condition  is,  both  in  respect  to  respiration  and  to 
bronchial  type  is  unfortunately  not  known  in  such  detailed  exactitude  as  is  required  by  this 
kind  of  a  problem.  In  this  connection  a  suggestion  made  by  Dr.  John  C.  Vaughan  of  this 
department  is  not  without  interest  and  with  his  permission  I  state  it.  When  the  animal  has 
filled  its  lungs  at  the  surface  and  then  dives,  its  thorax  and  diaphragm  are  in  the  position  of 
full  inspiration.  The  position  of  the  diaphragm  during  submergence  is  of  course  a  matter  of 
conjecture.  But  on  the  assumption  that  it  does  not  maintain  its  contraction,  it  is  evident 
that  the  pressure  of  the  water  upon  the  abdomen  would  force  the  relaxed  muscle  rostrad  in  the 
thorax,  and  that  this  would  necessitate  a  redistribution  of  the  air  in  the  lungs  entailing  a  passive 
movement  of  the  ribs  beyond  their  position  in  full  inspiration.  As  with  the  exception  of  the 
first,  the  ribs  are  free  of  sternal  connections  it  is  conceivable  that  their  ventral  extremities  might 
be  displaced  laterad  to  a  marked  degree,  even  so  far  as  to  take  up  the  slack  in  the  ventral  pouch, 
which  in  this  foetus  is  by  no  means  so  baggy  over  the  thorax  and  abdomen  as  in  the  intermandi- 
bular  region.  It  would  seem  therefore  that  Andrews's  association  of  the  ventral  furrows  on 
thorax  and  abdomen  with  respiratory  movements  has  much  in  its  favor  and  that  its  plausibilitv 
is  increased  by  Vaughan 's  suggestion  of  passive  distention  following  a  hypothetical  relaxation 
of  the  diaphragm. 

Sterno-mandibularis  and  associated  muscles. —  The  side  of  the  neck  is  occupied  by  a  very 
large  muscle  mass  of  complex  arrangement  which  extends  from  the  thorax  to  the  mandible  and 
to  the  postglenoid  region  of  the  cranium,  its  fasciculi  having  an  obliquely  dorso-rostral  direc- 
tion. This  muscle  which  for  want  of  a  better  name  may  be  called  sterno-mandibularis,  lies 
under  cover  of  the  panniculus  carnosus;  its  dorsal  margin  is  in  apposition  with  the  mastohu- 
meralis  and  trapezius;  mesad  it  enters  into  the  boundary  of  the  cavum  ventrale  and  by  its  deep 
surface  conceals  the  sterno-mastoid  and  farther  rostrad  overlies  the  caudal  portion  of  the  mylo- 
hoid  near  the  origin  of  the  latter  muscle.  From  its  mesal  border  fasciculi  are  added  to  the 
longitudinal  stratum  of  the  ventral  pouch,  in  this  as  in  its  nerve  supply  revealing  its  provenience 
from  the  cervico-hypoglossal  musculature.  It  is  not  however  a  modified  and  extended  sterno- 
hyodeus,  for  that  muscle  is  present  with  its  usual  attachments;  it  should  rather  be  considered 
a  cleavage  product  of  the  infrahyoid  group,  resulting  in  the  formation  of  a  superficial  stratum 
which  has  attained  enormous  size  and  acquired  extensive  new  origins  and  insertions.  At  its 
origin  it  is  obscurely  divided  into  two  heads,  partially  separated  by  the  rostral  border  of  the 
pectoralis.  The  mesal  fasciculi  arise  from  the  aponeurosis  covering  the  pectoral  muscle  and 
on  their  deep  surface  receive  additional  bundles  from  a  narrow  strip  of  sternum  between  the 
origins  of  the  pectoralis  and  sternomastoid.  The  lateral  fasciculi  arise  from  the  rostral  margin 
of  the  first  rib  near  its  sternal  extremity,  here  being  continuous  with  the  deep  origin  of  the  mesal 
head,  further  from  the  fascia  of  the  posterior  triangle  of  the  neck,  from  the  sheath  of  the  sterno- 
mastoid and  mesal  to  this  from  the  sheath  of  the  sterno-hyoid.  From  this  extensive  origin 
the  fasciculi  are  directed  dorsad  and  rostrad,  spreading  out  to  form  a  thick  fan  shaped  sheet 
which  splits  into  two  layers  to  give  passage  to  the  facial  nerve.  Of  the  superficial  stratum  the 
most  mesal  fasciculi  are  continuous  with  the  longitudinal  stratum  of  the  ventral  pouch.  The 
next  pass  over  the  lower  border  of  the  rrandible  join  the  panniculus  and  are  inserted  into  the 
lower  lip,  into  the  floor  of  the  furrow  which  prolongs  the  vestibule  below  the  eye,  while  the  most 


410  SCHULTE,  SEI  WHALE. 

dorsal  gain  an  insertion  into  the  postglenoid  process  of  the  squamosal  and  the  fibrous  struc- 
tures adjacent  to  the  temporo-maxillary  articulation.  The  deeper  stratum  has  interesting 
relations.  Its  dorsal  fasciculi  terminate  in  an  intermuscular  septum  which  attaches  them  to 
the  posterior  belly  of  the  digastric  in  almost  its  whole  length.  Its  ventral  fasciculi  which  appar- 
ently are  separated  from  the  rest  of  the  muscle  by  a  tendinous  inscription  (this  is  clearly  present 
in  Megaptera)  and  are  distinguished  as  well  by  a  more  longitudinal  course  are  divided  into  two 
slips.  The  dorsal  of  small  size,  applied  to  the  lateral  surface  of  the  posterior  belly  of  the  digastric 
and  united  to  it  by  a  common  septum  passes  horizontally  forward  to  be  inserted  into  the  body 
of  the  mandible  below  the  attachment  of  the  masseter.  This  slip  thus  arises  from  fibrous  inscrip- 
tions, which  unite  it  with  both  the  sterno-mandibularis  and  the  depressor  mandibulse  (posterior 
belly  of  the  digastric).  It  is  of  larger  size  and  of  better  definition  in  a  foetus  of  Megaptera  longi- 
mana  and  there  I  was  able  to  demonstrate  its  innervation  from  the  mylohyoid  branch  of  the 
fifth.  It  is  therefore  to  be  interpreted  as  the  anterior  belly  of  the  digastric.  The  remaining 
slip,  of  considerably  larger  size  in  Balcenoptera,  is  directed  rostrad  parallel  to  the  foregoing  and, 
in  part  overlapping  it,  is  lost  in  the  dense  fibrous  tissue  between  the  mylohyoid  and  panniculus. 
This  slip  was  small  in  Megaptera.  In  both  foetuses  it  was  innervated  by  a  branch  of  the  seventh 
nerve.  In  both  forms  there  was  a  general  correspondence  in  the  make  up  of  this  muscle  com- 
plex, and  I  have  relied  upon  the  data  obtained  from  the  Megaptera  foetus  for  confirmation  of  the 
findings  in  the  smaller  and  in  this  region  less  well  preserved  Balcenoptera.  The  chief  differences 
in  the  arrangement  in  the  two  forms  lies  in  the  development  of  a  muscle-free  interval  in  Megap- 
tera between  the  mandibular  and  postglenoid  divisions  of  the  muscle.  Here  a  triangular  apo- 
neurosis  is  present  and  is  continued  superficial  to  the  anterior  belly  of  the  digastric  and  the 
facialis  slip.  I  am  quite  sure  that  muscle  fasciculi  were  present  in  this  position  in  B.  borealis, 
though  infiltrated  with  fat,  the  precise  distribution  of  which  I  could  not  determine.  It  would 
seem  therefore  that  the  mandibular  insertion  in  Megaptera  defaults,  the  superficial  stratum  here 
being  replaced  by  fascia.  The  muscle  would  seem  therefore  to  consist  essentially  of  fasciculi 
of  thoracic  and  mesal  origin  directed  to  the  mandible  and  the  region  adjacent  to  the  temporo- 
maxillary  articulation.  This  system  of  fasciculi  is  innervated  by  the  hypoglossal  after  its  com- 
munication with  the  cervical  nerves,  several  small  branches  entering  at  the  lateral  border  of 
the  sterno-hyoid  and  others  being  derived  from  the  large  division  of  that  nerve  which  runs  over 
its  ental  surface.  To  this,  on  its  deep  surface,  slips  of  quintal  and  facial  innervation  have 
gained  attachment;  the  former  attached  also  to  the  depressor  mandibulse  constitutes  the  ante- 
rior belly  of  the  digastric. 

Muscles  of  mastication. —  The  masseter  is  composed  of  two  layers  which  are  completely 
separate,  the  superficial  small,  triangular  and  very  oblique  in  position,  the  deep  quadrilateral, 
of  large  size  and  intersecting  the  superficial  portion,  by  which  it  is  deeply  grooved,  almost  at 
right  angles.  In  recognizing  but  two  layers  I  am  in  agreement  with  Carte  and  MacAlister; 
the  middle  division  of  Beauregard's l  careful  description  of  B.  musculus  seems  here  to  form  an 
intrinsic  part  of  the  deep  stratum.  The  superficial  portion. arises  by  a  small  flattened  tendon 
from  the  orbital  aponeurosis,  just  mesal  to  the  zygoma  at  the  junction  of  its  middle  and  caudal 
thirds.  Here  it  is  continuous  with  strong  band-like  thickenings  of  the  aponeurosis,  which  col- 
lectively form  a  sagittal  arch  of  tendinous  structure  and  ventral  convexity.  Its  caudal  arm  is 

1  Beauregard,  H.     Etude  de  1'Articulation  temporo-maxillaire  chez  les  Balaenopteres.     Jour,  de  1'Anat.  et  de  la  Phys.,  An.  18, 
1882,  p.  16. 


PLATE  XLIV. 


PLATE  XLIV. 


Balasnoptera  borealis. 

Fig.  1.     Dissection  of  musculature  of  ventral  pouch  and  the  sterno-manclibularis.     f  natural  size. 
Fig.  2.     Superficial  muscles  of  face,  hyoid  musculature,  muscles  of  flipper,  of  neck  and  of  intermandibular  region. 
The  panniculus  carnosus  and  the  muscles  of  the  ventral  pouch  have  been  removed,     f  natural  size. 


1.  Ventral  division  of  the  panniculus  reflected.  16. 

2.  M.  mylohyoideus  reflected.  17. 

3.  Longitudinal  layer  of  ventral  pouch  partially  reflected.  18. 

4.  Cavum  ventrale.  19. 

5.  M.  sternomandibularis.  20. 

6.  M.  pectoralis.  21. 

7.  M.  latissimus  dorsi.  22. 

8.  M.  teres  major.  23. 

9.  M.  infraspinatus.  24. 

10.  M.  deltoideus.  25. 

11.  M.  trapezius.  26. 

12.  M.  masto-humeralis.  27. 

13.  M.  sterno-mastoideus.  28. 

14.  M.  splenius.  29. 

15.  M.  trachelo-mastoideus. 


M.  occipito-frontalis. 

M.  orbicularis  palpebrarum. 

Superficial  layer  of  transverse  rostral  muscle. 

M.  masseter. 

M.  depressor  mandibulse. 

M.  geniohyoglossus. 

M.  hyoglossus. 

M.  omohyoideus. 

M.  sternohyoideus. 

M.  rhomboideus. 

M.  triceps. 

M.  extensor  communis  digitorum. 

M.  flexor  carpi  ulnaris. 

M.  obliquus  externus. 


Memoirs  Am.  Mus.  Nat.  Hist. 


N.  S.,  Vol.  I,  Plate 


SCHULTE,  SEI  WHALE.  411 

attached  to  the  squamosal  at  its  junction  with  the  zygoma.  Its  rostral  prolongation  divides 
into  three  slightly  diverging  strands,  of  which  the  lateral  reaches  the  zygoma  in  its  rostral  third, 
the  middle  is  attached  to  the  junction  of  the  zygoma  with  the  maxilla,  and  the  mesal  inserts 
upon  the  orbital  border  of  the  maxilla.  Beauregard  describes  this  tendinous  complex  as  being 
placed  ventral  to  the  orbital  aponeurosis,  but  in  this  specimen  it  seemed  to  be  incorporated  in 
it  and  capable  of  pulling  it  ventrad  on  the  contraction  of  the  muscle.  From  the  tendon  the  mus- 
cular fasciculi  diverge  fan-wise,  having  a  general  ventro-caudal  direction  and  forming  a  belly 
large  in  proportion  to  the  tendon.  They  are  inserted  into  the  lateral  surface  of  the  mandible 
between  the  deep  portion  of  the  masseter  and  the  depressor  mandibulse,  the  latter  preventing 
them  from  extending  to  the  border  of  the  body  or  of  the  ramus  except  at  the  extreme  caudal 
angle  of  this  insertion.  From  its  size  and  position  this  portion  of  the  masseter  would  seem  to 
find  its  chief  function  as  a  tensor  of  the  orbital  aponeurosis.  The  orbit  on  its  ventral  aspect 
bulges  into  the  roof  of  the  vestibulum  oris,  and  the  protection  to  its  contents,  attained  by  keeping 
the  aponeurosis  taut,  may  serve  as  compensation  for  the  deficiency  of  its  osseous  encasement. 

The  deep  portion  of  the  masseter  can  be  resolved  into  two  parts.  The  rostral  arises  from 
the  junction  of  zygoma  and  squamosal,  from  the  postorbital  process  of  the  squamosal  and  from 
the  tendon  of  the  dorsal  muscles  which  is  there  attached.  Its  fasciculi  are  directed  ventrad  and 
rostrad  and  are  inserted  into  the  lateral  surface  of  the  mandible,  from  the  concavity  at  the  side 
of  the  coronoid  process  to  the  border  of  the  mandible  rostral  to  the  superficial  portion  of  the 
masseter.  The  fasciculi  of  more  rostral  insertion  correspond  in  position  to  the  intermediate 
layer  of  Beauregard,  but  I  could  not  follow  them  to  a  tendon  or  to  an  origin  distinct  from  the 
remainder  of  the  layer.  The  caudal  portion  of  the  deep  layer  arises  from  the  tendon  of  the 
dorsal  muscles  and  from  the  middle  root  of  the  zygomatic  process  of  the  squamosal,  and  is 
inserted  into  the  margin  of  the  sigmoid  notch  and  adjacent  lateral  surface  of  the  mandible. 
It  has  a  triangular  form  with  the  base  at  the  origin,  and  is  in  part  under  cover  of  the  rostral 
portion  of  the  deep  layer,  from  which  it  can  not  be  wholly  separated,  as  the  two  portions  exchange 
fasciculi  to  a  considerable  degree;  these  pass  chiefly  from  the  origin  of  the  caudal  to  the  belly 
of  the  rostral  portion. 

The  temporal  muscle  is  the  largest  of  the  quintal  muscles  but,  as  is  usual  in  young  animals, 
fails  to  fill  the  temporal  fossa,  occupying  with  its  rather  thin  sheet  of  bundles  only  the  lower 
and  deeper  portion  of  the  fossa  and  being  covered  by  a  thick  and  compact  layer  of  fat.  The 
limit  of  its  origin  is  an  arched  line  coinciding  rostrad  with  the  anterior  temporal  ridge  and  then 
falling  off  obliquely  to  the  mastoid  region.  The  fasciculi  converge  upon  a  tendon,  which  appears 
at  the  rostral  border  of  the  muscle  and  is  inserted  into  the  summit  and  rostral  border  of  the 
coronoid  process.  Many  of  the  caudal  fasciculi  continue  to  the  mandible  and  are  inserted 
fleshy  into  both  surfaces,  chiefly  the  ental,  and  into  the  caudal  margin  of  the  process. 

The  internal  pterygoid  is  of  moderate  size.  It  arises  from  the  caudal  margin  of  the 
palate  and  the  adjacent  surface  of  the  internal  pterygoid  plate.  It  is  directed  as  a  flat 
band  laterad  and  caudad  towards  the  mandible;  here  assuming  a  more  sagittal  direction  it 
passes  between  the  mandible  and  the  auditory  bulla,  to  the  fibrous  covering  of  which  it  adheres 
firmly  and  from  which  it  receives  an  increment  to  its  bundles.  It  now  broadens  into  a  thin 
sheet  and  turning  laterad  it  is  inserted  into  the  mesal  surface  of  the  mandible  in  a  depression 
between  Meckel's  cartilage  and  the  angular  process,  into  the  angular  process  itself  and  the  caudal 
margin  of  the  ramus,  and  behind  this  into  the  dense  fibrous  tissue  surrounding  the  temporo- 


412  SCHULTE,  SEI  WHALE. 

maxillary  fibro-cartilage.  From  its  caudal  margin  a  fasciculus  of  considerable  relative  size 
diverges  at  an  angle  and  becoming  tendinous  is  inserted  into  the  dense  fibrous  tissue  which 
invests  the  auditory  bulla,  on  its  ventro-lateral  aspect  extending  as  far  as  the  base  of  the  styloid 

process. 

The  external  pterygoid,  is  placed  at  the  lateral  margin  and  partly  under  cover  of  the  fore- 
going. It  is  a  small  cylindrical  muscle  arising  from  the  junction  of  external  and  internal 
pterygoid  plates,  and  is  directed  caudad,  laterad  and  slightly  ventrad  to  its  insertion  upon  the 
front  of  the  temporo-maxillary  fibro-cartilage. 

Carte  and  MacAlister  describe  a  single  pterygoid,  which  "was  inserted  into  the  lower  jaw 
near  its  angle,  sending  some  of  its  posterior  fibers  to  be  inserted  into  the  interarticular  fibro- 
cartilage."  This  they  regard  as  an  external  pterygoid.  It  is  preferable,  however,  to  regard 
such  single  pterygoids  as  having  failed  to  differentiate  into  internal  and  external  portions. 
Certainly  the  majority  of  the  bundles  in  their  description  of  B.  acuto-rostrata  have  the  in- 
sertion of  the  internus.  Beauregard  in  B.  sibaldii  (=B.  musculus)  mentions,  but  does  not 
describe,  two  pterygoids  crossing  the  temporal  tendon  at  an  acute  angle.  In  Phoccena  (Rapp, 
Stannius)  both  pterygoids  are  present,  and  the  internus  extends  upon  the  auditory  bulla. 

Facial  Muscles. —  The  forehead  is  covered  by  a  broad  thin  sheet  of  muscle  which  arises 
from  the  epicranial  aponeurosis.  The  fasciculi  have  a  longitudinal  course  and  extend  upon  the 
rostrum.  Here  the  deep  fasciculi  turn  ventrad  and  are  inserted  into  a  rough  area  upon  the 
maxilla  which  extends  transversely  across  that  bone  and  is  bounded  in  front  by  a  high  sharp 
ridge.  Of  the  superficial  fasciculi  the  mesal  are  inserted  into  the  lateral  margin  of  the  nostril 
in  its  whole  length,  a  few  reaching  the  midline  of  the  rostrum  just  in  front  of  it,  while  others 
taking  a  somewhat  deeper  course  are  attached  to  the  back  and  mesal  wall  of  the  narial  passage. 
The  lateral  superficial  fasciculi  spread  out  upon  the  transverse  muscle  of  the  rostrum,  to  some 
extent  blending  with  its  bundles  but  in  the  main  lying  superficial  to  them.  Caudad  the  epi- 
cranial aponeurosis  is  attached  to  the  margin  of  the  supraoccipital.  In  this  situation  there 
seemed  also  to  be  muscular  fasciculi  but  I  was  not  able  to  determine  their  presence  with  cer- 
tainty. This  muscle  is  apparently  better  developed  than  in  Carte  and  MacAlister's  Balcenop- 
tera  and  far  more  so  than  in  Megaptera,  where  it  has  no  insertion  upon  the  maxillary.  In  both 
it  is  the  most  superficial  muscle  of  the  region,  though  Carte  and  MacAlister  assign  it  to  their 
second  or  middle  layer.  Its  function  must  be  to  draw  the  blow  holes  caudad,  though  from 
its  general  position  it  is  most  conveniently  designated  occipitofrontalis. 

At  the  lateral  margin  of  the  frontalis  and  in  part  continuous  with  it  is  placed  a  second  muscle 
of  longitudinal  course.  This  lies  upon  the  supraorbital  margin  arising  from  it  and  from  the 
adjacent  temporal  fascia.  In  front  of  the  orbit  its  fasciculi  turn  ventrad,  for  the  most  part 
to  be  inserted  into  the  transverse  rough  area  and  ridge  upon  the  maxillary  lateral  to  the  frontalis. 
The  more  superficial  bundles  are  continued  upon  the  transverse  muscle  of  the  rostrum  and 
inserted  into  the  fibrous  tissue  of  the  lip.  Owing  to  the  mesal  concavity  of  the  supraorbital 
margin  a  portion  of  this  muscle  rests  against  the  globe  of  the  eye,  ectal  to  its  musculature  and 
aponeuroses.  Its  contraction  would  seem  to  entail  a  depression  of  the  eye  ventrad.  In  Megap- 
tera it  is  far  smaller,  arises  only  from  fascia  and  is  separated  from  the  eye  by  the  prominent 
margin  of  the  orbit.  Its  function  here  would  seem  to  be  that  of  an  elevator  of  the  lip.  Carte 
and  MacAlister  describe  a  muscle  of  their  second  plane  arising  from  the  anterior  edge  of  the 
temporal  fossa  and  from  the  maxilla  and  inserting  upon  the  median  raphe",  the  lateral  lip  of  the 


SCHULTE.  SEI  WHALE.  413 

naris  and  the  upper  edge  of  the  maxillary  bone.  As  I  could  find  no  fasciculi  of  the  supraorbital 
muscle  having  this  mesal  course,  and  as  there  are  such  bundles  in  the  next  deeper  layer,  it  would 
seem  possible  that  here  they  had  failed  to  separate  the  superimposed  muscles  satisfactorily. 

The  dorsum  of  the  rostrum  is  covered  by  a  muscle  composed  of  fasciculi  of  transverse  gen- 
eral direction  but  converging  towards  the  blow-holes.  This  muscle  is  situated  immediately 
below  the  blubber  except  at  the  base  of  the  rostrum  where  it  is  overlapped  for  a  short  distance 
by  the  frontalis  and  the  laterally  placed  supraorbital  muscle.  It  may  be  resolved  into  two 
layers.  The  superficial  one  arises  from  the  septal  cartilage  of  the  rostrum  and  the  lateral  margin 
of  the  blow-hole.  It  is  inserted  into  the  whole  length  of  the  lip  and  at  the  tip  of  the  rostrum 
also  by  a  few  fasciculi  into  the  extremity  of  the  intermaxillary.  The  deeper  layer  has  the  same 
general  direction.  It  arises  from  the  intermaxillary  in  its  whole  length  and  at  its  lateral  margin 
to  a  slight  degree  from  the  maxilla,  except  at  the  base  of  the  rostrum  where  it  gains  a  broad 
origin  from  this  bone,  arising  from  the  front  of  the  sharp  transverse  ridge  for  more  than  half 
its  breadth  laterad,  and  mesad  extending  to  the  elevation  behind  the  nares  in  which  the  frontal 
process  of  the  maxilla  ends.  The  fasciculi  arising  in  this  last  situation  would  seem  to  corre- 
spond in  part  to  the  retractores,  in  part  to  the  compressores  nasi  of  Carte  and  MacAlister.  The 
fasciculi  arising  most  caudally  from  the  maxillary  ridge  are  directed  sagitally,  those  from  its 
lateral  portion  mesad  and  rostrad ;  they  thus  converge  fan-like  towards  the  rostral  extremity 
of  the  blow  hole.  From  their  direction  it  is  clear  that  they  dilate  the  nares,  but  the  sagittal 
fasciculi  would  seem  farther  to  assist  the  superficial  frontalis  in  elevating  the  orifice  and  turning 
it  caudad  during  respiration.  The  remainder  of  the  layer  inserts  into  the  raphe  its  fasciculi 
having  a  generally  transverse  direction  but  converging  towards  the  nares.  Megaptera  shows  a 
close  correspondence  save  that  relatively  its  muscles  are  of  smaller  size. 

In  addition  to  the  foregoing  three  smaller  muscles  act  upon  each  blow-hole.  The  larg- 
est of  these,  the  dilator  naris  of  Carte  and  MacAlister's  illustration  arises  from  the  premaxillary 
close  to  the  median  line  and  in  the  proximal  half  of  its  prenarial  extent,  and  from  the  adjacent 
portion  of  the  septal  cartilage.  It  has  a  sagittal  course  and  inserts  into  the  rostral  end  and  about 
half  the  lateral  wall  of  the  narial  passage,  including  the  front  of  its  sloping  diverticulum.  Its 
main  function  must  be  to  draw  forward  the  blow-hole;  dilation  would  seem  to  be  abundantly 
provided  by  the  transverse  rostral  muscle. 

At  the  caudal  extremity  of  the  blow-hole  is  a  small  fan-shaped  muscle  superficial  to  the 
frontalis.  It  arises  from  the  fibrous  tissue  of  the  median  line  and  inserts  into  the  extremity  of 
the  nostril  and  the  adjacent  portion  of  its  median  wall. 

The  third  muscle  is  placed  below  and  parallel  to  the  oblique  lateral  sinus  of  the  nasal  pas- 
sage, from  the  wall  of  which  it  arises  and  also  from  the  adjacent  margin  of  the  premaxillary. 
It  is  directed  dorsad  and  caudad  and  slightly  mesad  to  the  extremity  of  the  blow-hole,  where 
it  inserts  by  a  short  tendon,  close  to  the  preceding  muscle.  Its  action  would  be  to  draw  the 
caudal  end  of  the  nostril  ventrad  and  so  perhaps  assist  in  the  elevation  of  its  rostral  extremity, 
the  obliquity  of  its  pull  being  perhaps  corrected  by  the  small  fan-shaped  muscle  mesal  to  the 
blow  hole.  In  Megaptera  these  three  muscles  have  an  identical  arrangement. 

The  collective  action  of  the  narial  muscles  must  be  considered  in  connection  with  the  changes 
in  the  blow  holes  during  respiration.  Their  condition  during  this  act  is  admirably  shown  in 
Andrews's :  photograph.  Here  the  blow-hole  has  a  subcircular  contour  and  looks  directly 

1  Plate  XXX,  Fig.  4. 


414  SCHULTE,  SEI  WHALE. 

caudad,  the  plane  of  its  orifice  being  practically  vertical.  The  blow-hole  is  then  not  only  dilated 
during  respiration  but  its  rostral  extremity  is  elevated  through  an  arc  of  90°.  To  permit  the 
latter  movement  it  is  necessary  that  its  wall  should  be  highly  elastic  or  should  present  some  sign 
of  redundancy  when  closed,  in  the  form  of  folds  which  might  open  out  during  elevation  of  the 
region.  The  Spritzsack,  the  oblique  diverticulum  of  the  lateral  wall,  would  seem  to  supply  the 
latter  condition,  for  it  is  partially  opened  up  by  traction  upwards  on  the  rostral  extremity  of 
the  blow-hole  even  with  the  limited  degree  of  movement  possible  in  the  alcoholic  specimen. 
The  direction  of  the  fasciculi  of  the  two  layers  of  the  transverse  rostral  muscles  justify  the 
ascription  to  them  of  the  dilatation  of  the  nares,  and  in  view  of  the  almost  total  lack  of  muscular 
insertion  into  the  mesal  wall  of  the  passage  it  seems  clear  that  this  act  is  accomplished  almost 
entirely  by  the  movement  of  the  lateral  parietes.  As  regards  the  elevation  of  the  rostral  extrem- 
ity of  the  blow-hole,  the  initiation  of  the  act  is  more  difficult  of  explanation.  Once  started, 
and  the  front  end  of  the  nares  slightly  elevated,  the  sagittal  fasciculi  of  the  frontalis  and  caudal 
portion  of  the  deep  transverse  muscle  could  well  serve  to  complete  their  erection,  but  inasmuch 
as  even  in  the  foetus  their  origin  is  but  little  above  the  plane  of  the  blow-hole,  they  would  act 
at  great  disadvantage  if  not  absolutely  at  dead  center.  The  difficulty  is  to  account  for  the 
initial  elevation.  If  some  resiliency  of  the  wall  may  be  assumed,  and  this  in  view  of  Andrews's 
observation  1  seems  warrantable,  the  action  of  the  oblique  muscle  below  the  Spritzsack  may 
supply  the  required  moment.  From  its  oblique  position  it  must  draw  the  caudal  end  of  the 
blow-hole  ventrad  and  laterad.  If  the  narial  wall  possesses  sufficient  rigidity  to  allow  this 
movement  to  tilt  dorsad  the  rostral  extremity,  the  preliminary  elevation  might  in  this  way 
be  secured.  The  small  muscle  extending  between  the  midline  and  the  caudal  extremity  of  each 
blow-hole  may  correct  the  lateral  component  in  the  pull  of  the  oblique  muscle.  The  return  of 
the  nares  to  the  horizontal  position  is  provided  by  the  sagittal  premaxillary  muscle,  and  with 
this  fixing  its  rostral  extremity  the  mesal  fasciculi  of  the  frontalis  would  serve  to  effect  an 
approximation  of  the  lateral  to  mesal  wall  of  the  narial  passage,  closure  being  further  provided 
by  the  interlocking  arrangement  of  the  folds  about  the  Spritzsack,  which  is  such  as  to  secure 
their  tighter  coaptation  under  the  influence  of  external  pressure. 

The  other  facial  muscles  are  poorly  developed  and  of  great  delicacy  in  this  foetus  so  that 
little  more  than  their  presence  could  be  ascertained.  The  orbicularis  palpebrarum  was  thickest 
at  the  canthi,  where  it  had  attachments  to  the  orbital  margin.  At  the  inner  canthus  a  tendo 
oculi  was  present.  There  were  no  tarsal  plates.  At  the  outer  canthus  a  small  band  of  muscular 
fibres  arising  from  the  postorbital  process  joined  the  orbicularis.  It  seems  to  correspond  to 
the  malaris  externus  of  Stannius.  In  the  margin  of  the  lips,  mingled  with  fasciculi  of  the  trans- 
verse rostral  muscle  in  the  case  of  the  upper  lip,  of  the  panniculus  in  the  lower,  are  longitudinal 
strands.  In  the  floor  of  the  subocular  prolongation  of  the  vestibule  these  unite  to  form  a  small 
sheet,  which  caudad  can  be  traced  to  the  deep  surface  of  the  panniculus.  I  could  not  follow 
it  to  pharynx.  The  system  would  therefore  seem  representative  of  the  orbicularis  oris,  the 
buccinator  being  reduced  in  consequence  of  the  failure  to  develop  a  cheek  by  the  advance  of 
the  angulus  oris. 

Extrinsic  muscles  of  the  eye. —  These  conform  so  closely  to  Weber's  2  descriptions  that  they 
require  but  brief  mention  here.  The  four  recti  with  the  superior  oblique  arise  from  an  annulus 

1  Vide  Pt.  I,  Spouting.  2  Weber,  M.     Studien  iiber  Saugethiere,  II,  Jena,  1886. 


SCHULTE,  SEI  WHALE.  415 

tendineus  at  the  apex  of  the  orbit,  which  on  its  ental  aspect  is  associated  with  the  fibrous  origin 
of  the  retractor.  The  four  recti  broadening  towards  their  insertion,  together  with  the  superior 
oblique,  form  a  complete  muscular  cone  which  is  deficient  only  by  a  narrow  gap  between  the 
oblique  and  the  internal  rectus.  Elsewhere  the  border  of  one  muscle  is  in  contact  with  that 
of  its  neighbor  and  the  whole  is  held  in  place  by  a  thin  but  firm  investment  of  fascia,  through 
which  the  obliqui  pass  to  their  insertions  upon  the  sclera.  Of  each  of  the  recti  a  majority  of 
the  fasciculi  pass  on  into  the  lids  and  there  expanding  find  an  insertion  into  the  fibrous  tissue 
on  the  deep  surface  of  the  orbicularis.  These  extensions  to  the  eyelids,  first  found  by  Hunter, 
constitute  collectively  the  musculus  palpebralis  of  Weber. 

Weber  describes  exchange  of  bundles  between  the  recti  which  I  take  him  to  mean  of  their 
palpebral  portions,  for  elsewhere  in  this  foetus  the  muscles  were  clearly  defined  from  one  another. 
The  superior  rectus  was  partially  divided  in  both  eyes  by  a  longitudinal  cleft,  so  that  at  first 
it  appeared  as  though  a  discrete  levator  were  present.  This  was  not  the  case,  for  both  portions 
sent  bundles  to  eyelid  as  well  as  globe,  and  the  cleft  did  not  extend  throughout  the  length  of 
the  muscle.  The  inferior  oblique  arises  from  the  maxilla  near  its  articulation  with  the  zygoma. 
It  is  directed  laterad  and  caudad  to  the  border  of  the  inferior  rectus,  where  it  turns  on  itself, 
passing  between  the  deep  and  superficial  fasciculi  of  the  palpebral  extension,  by  which  it  is  main- 
tained in  position.  Its  belly  then  expands  into  a  broad  insertion  upon  the  sclera,  which  begins 
ectal  to  the  mesial  half  of  the  inferior  rectus  and  continues  obliquely  to  the  level  of  the  ventral 
border  of  the  external  rectus.  All  of  the  peculiarities  of  this  muscle  have  been  minutely 
described  by  Weber.  From  the  deep  surface  of  its  sheath  a  few  fibrous  strands  could  be  fol- 
lowed to  the  zygoma,  which  no  doubt  reinforced  the  muscular  support  afforded  by  the  cleft 
in  the  palpebralis.  The  insertion  beginning  ectal  to  the  inferior  rectus  occurs  in  other  cetacea 
but  is  not  confined  to  this  order  (Weber).  In  this  foetus  it  is  broad  and  continuous  as  in  B. 
Sibbaldii  (  =  B.  musculus)  and  not  divided  into  two  slips  as  in  B.  rostrata  (=  acuto-rostrata). 
The  superior  oblique,  like  the  inferior,  is  fleshy  to  its  insertion.  The  belly  turns  through  the 
palpebral  extension  of  the  superior  rectus  and  is  maintained  in  position  in  a  manner  similar 
to  the  inferior.  I  could  not  find  a  fibrous  trochlea,  though  it  is  present  in  adults  of  the  genus 
(Weber). 

The  musculus  retractor  oculi  (m.  choanoides)  arises  from  the  ental  contour  of  the  annulus 
tendineus.  Its  fibrous  tube  is  deficient  on  its'  nasal  aspect  to  give  passage  to  the  optic  nerve. 
From  this  tube  a  circular  muscle  arises,  which  distad  divides  into  four  slips,  separated  by  tri- 
angular intervals.  Throughout  its  length  it  is  firmly  adherent  to  the  supportive  tissue  of  the 
underlying  vascular  plexus.  It  is  inserted  into  the  sclera  near  the  equator  of  the  globe.  It  is 
innervated  by  the  abducens  (Weber). 

Muscles  of  the  tongue. —  The  genioglossus  is  a  broad  sheet-like  muscle  arising  from  the 
ental  aspect  of  the  ventral  margin  of  the  mandible  from  the  symphysis  for  about  one  half  of 
its  length.  Its  mesal  fasciculi  pass  sagittally  caudad,  those  of  more  lateral  origin  obliquely 
mesad  and  caudad.  On  reaching  the  mesal  margin  of  the  hyoglossus  all  save  the  most  caudal 
fasciculi  turn  dorsad  to  be  inserted  into  the  dorsum  of  the  tongue.  Here  between  the  muscles 
of  the  two  sides  is  a  considerable  oval  interval  filled  with  fat,  to  the  increased  development  of 
which  may  be  due  the  peculiarly  flabby  character  of  the  tongue  in  the  adults  of  this  genus.  The 
most  caudal  fasciculi  unite  in  a  raphe  which  broadens  to  a  tendinous  sheet  towards  the  hyoid 
to  which  it  is  but  loosely  attached,  the  dorsal  turn  into  the  substance  of  the  tongue  being  pre- 


416  SCHULTE,  SEI  WHALE. 

vented  at  this  point  by  the  transverse  lingualis  bundles  accumulated  here  in  the  immediate 
vicinity  of  the  faucial  orifice.  Rostrad  of  the  extremity  of  the  fossa  between  the  genioglossi, 
the  ventral  surfaces  of  these  muscles  are  intimately  united  to  the  layers  composing  the  wall 
of  the  ventral  pouch;  elsewhere  they  are  in  relation  to  the  cavum  ventrale.  There  are  no  sepa- 
rate geniohyoidei. 

The  hyoglossus  is  a  long  cylindrical  muscle  arising  from  the  ectal  surface  of  the  greater 
cornu  and  lateral  portion  of  the  body  of  the  hyoid,  and  continued  forward  to  the  tip  of  the 
tongue.  Close  to  its  origin  it  crosses  the  transverse  fasciculi  of  the  lingualis  mentioned  above. 
Immediately  rostrad  of  these  its  insertion  begins,  which  is  into  the  dorsum  of  the  tongue  from 
this  point  to  its  tip.  The  hypoglossal  nerve  lies  upon  the  ventral  surface  of  this  muscle  at  its 
origin,  here  giving  off  large  branches,  which  are  continued  into  the  interval  between  the  hyo- 
glossus and  genioglossus  and  are  destined  for  their  supply  together  with  that  of  the  lingualis. 
A  small  slip  passes  from  the  deep  surface  of  the  hyoglossus  to  the  caudal  border  of  the  trans- 
verse lingualis  band,  well  laterad  at  its  junction  with  the  palatoglossus.  I  failed  to  find  the 
styloglossus.  Carte  and  MacAlister  describe  it  as  of  small  size,  fan-shaped  and  lateral  to  the 
other  muscles,  sending  its  fasciculi  into  the  caudal  third  of  the  tongue. 

The  palatoglossus  is  of  moderate  size;  arising  from  the  caudal  margin  of  the  hard  palate, 
it  is  directed  ventrad  towards  the  base  of  the  tongue  where  it  continues  with  the  transverse 
lingualis.  It  lies  immediately  beneath  the  oral  mucous  membrane  forming  a  thin  transverse 
sheet,  the  most  mesal  fasciculi  apparently  inserting  into  the  mucosa  about  the  faucial  aperture, 
the  more  lateral  passing  beside  it  reach  the  side  of  the  depression  between  the  base  of  the 
tongue  and  this  aperture  and  blend  with  the  lingualis,  thus  forming  a  sphincter  of  the  fauces. 
It  shows  no  tendency  to  radiate  rostrad  along  the  side  of  the  tongue. 

The  lingualis  is  of  course  intimately  blended  with  the  other  muscles  of  the  tongue. 
Towards  the  base  it  shows  a  high  degree  of  independence  and  can  be  separated  from  the  other 
muscles  as  far  rostrad  as  the  insertion  of  the  hyoglossus.  It  there  presents  itself  as  a  transverse 
band  forming  a  thick  wall  to  the  depression  between  the  fauces  and  the  paired  elevations  where 
the  tongue  begins  to  rise  above  the  floor  of  the  mouth.  Mesad  its  more  superficial  fasciculi 
arise  from  the  deep  surface  of  the  aponeurotic  expansion  of  the  raphe  between  the  genio-hyoidei. 
Its  caudal  portion  is  continuous  with  the  palatoglossus  and  is  joined  by  the  slip  above  men- 
tioned from  the  deep  surface  of  the  hyoglossus.  The  remainder  inserts  into  the  mucous  mem- 
brane of  the  side  and  dorsum  of  the  tongue,  the  most  rostral  fasciculi  inclining  forwards  beside 
the  hyoglossus. 

Infrahyoid  muscles.—  The  sterno-hyoid  muscle  is  a  flat  band  of  longitudinal  fasciculi  aris- 
ing from  the  rostral  border  of  the  sternum  under  cover  of  the  sterno-mastoid,  and  contracting 
slightly  as  it  is  inserted  into  the  caudal  border  of  the  body  of  the  hyoid  close  to  the  median 
line.  Its  mesal  border  is  in  contact  with  that  of  its  antimere.  The  sterno-mandibularis  overlies 
its  latero-caudal  portion  where  it  emerges  from  beneath  the  sterno-mastoid  and  derives  some 
fasciculi  from  its  sheath.  The  sterno-thyroid,  covered  by  the  sterno-hyoid,  arises  from  the  mar- 
gin and  ental  surface  of  the  sternum,  and  diverging  laterad  is  inserted  into  the  ectal  surface  of 
the  thyroid  cartilage  close  to  its  caudal  margin.  The  thyro-hyoid  is  a  small  muscle  of  obliquely 
transverse  position.  It  arises  from  the  thyroid  near  its  rostral  margin,  and  narrowing  has  a  small 
insertion  upon  the  caudal  margin  of  the  hyoid  close  to  the  midline  under  cover  of  the  sterno-hyoid. 
The  omo-hyoid  has  but  a  single  belly.  It  arises  from  the  rostral  margin  of  the  scapula  near  its 


SCHULTE,  SEI  WHALE.  ±17 

middle  and  receives  in  addition  a  small  slip  from  the  angle,  the  two  origins  being  connected  by  a 
sheet  of  fibrous  tissue.  Emerging  in  the  interval  between  the  deltoid  and  supraspinatus  muscles, 
its  belly  crosses  the  neck  obliquely  and  is  inserted  into  the  whole  length  of  the  greater  cornu  of 
the  hyoid.  These  muscles  all  receive  branches  from  the  anser  cervicalis. 

Suprahyoid  muscles. —  Of  these  the  geniohyoid  is  lacking  and  the  mylohyoid  has  been 
described  in  connection  with  the  ventral  pouch.  The  depressor  mandibulse  (posterior  belly 
of  the  digastric)  is  a  large  muscle  placed  obliquely  below  the  external  auditory  meatus  and  the 
broad  extremity  of  the  postglenoid  process.  It  arises  by  mixed  tendinous  and  fleshy  fibres  from 
the  dense  connective  tissue  covering  the  mastoid  region  of  the  periotic  under  cover  of  the 
sternomastoid.  The  belly  expands  in  its  course  to  the  mandible  where  it  is  inserted  into  the 
angle,  chiefly  at  its  caudal  and  ventral  borders,  but  extending  upon  the  lateral  surface  also 
ectal  to  the  attachment  of  the  masseter.  A  large  branch  of  the  facial  nerve  emerges  between 
its  belly  and  the  postglenoid  process,  crosses  the  condyle  of  the  jaw  and  the  masseter  muscle 
and  breaks  up  into  branches  for  the  panniculus.  From  this  while  in  contact  with  its  rostral 
surface  the  nerve  of  the  depressor  is  derived.  The  relations  of  this  muscle  to  the  sternomandibu- 
laris  and  the  anterior  belly  of  the  digastric  have  already  been  described. 

The  stylohyoid  is  a  ribbon  like  muscle  arising  from  the  mastoid  region  of  the  periotic 
ventral  and  mesal  to  the  depressor  mandibulse  and  caudal  to  the  orifice  of  the  facial  canal.  It 
is  inserted  into  the  body  of  the  hyoid  close  to  its  junction  with  the  anterior  cornu  and  to  the 
adjacent  portion  of  that  process.  Throughout  its  course  it  is  closely  applied  to  the  lateral  and 
caudal  aspect  of  the  stylohyal  cartilage.  It  is  innervated  by  a  branch  of  the  facial  nerve. 

The  trapezius  complex. —  These  muscles  derive  their  innervation  from  the  spinal  accessory 
reinforced  by  branches  from  the  ventral  divisions  of  the  cervical  nerves.  The  sterno-mastoid 
is  a  broad  ribbon-shaped  muscle,  arising  from  the  cephalic  border  of  the  sternum  in  its  whole 
breadth,  where  it  abutts  upon  the  origin  of  the  pectoralis.  It  crosses  the  neck  obliquely,  narrow- 
ing somewhat  to  its  insertion  by  mixed  tendinous  and  fleshy  fibres  into  the  squamosal  and  the 
dense  fibrous  tissue  which  covers  the  mastoid.  Here  it  is  covered  by  a  muscle  of  similar  but 
more  superficial  origin  which  directed  caudad  and  ventrad  towards  the  shoulder  enters  into 
relation  with  the  trapezius.  At  the  shoulder  this  muscle  resolves  itself  into  two  portions,  a 
deeper  rounded  belly  which  joins  the  trapezius  and  a  superficial  sheet  which  expanding  is 
inserted  into  the  fascia  along  the  rostral  margin  of  the  pectoral  in  its  lateral  half,  extending  to 
the  mesal  border  of  the  deltoid.  The  fascia  of  the  posterior  triangle  of  the  neck  is  of  consid- 
erable density  and  in  its  course  ventrad  splits  to  enclose  the  sterno-mastoid  in  the  usual  manner. 
Traced  towards  the  thorax  it  becomes  thickened  along  the  cephalic  margin  of  the  pectoralis; 
adjacent  to  the  median  line  it  is  firmly  attached  to  the  sternum  and  laterad  at  the  shoulder  blends 
with  the  dense  sheath  of  the  deltoid.  Beyond  this  transverse  line  it  continues  upon  the  pecto- 
ralis but  is  somewhat  less  dense  and  aponeurotic.  The  fasciculi  of  fascial  insertion  are  obviously 
representative  of  the  cleido-mastoid,  the  slip  joining  the  trapezius  is  the  masto-humeralis.  Of 
the  trapezius  proper  or  cephalo-humeralis  only  the  cephalic  portion  is  represented.  This  is 
a  small  fan  shaped  muscle  arising  from  the  dorsal  aponeurosis  of  the  cervical  region  without 
direct  attachment  to  bone.  Its  fibres  are  directed  ventrad  and  slightly  caudad  converging  to 
a  small  rounded  tendon,  which  after  uniting  with  the  larger  masto-humeralis  passes  in  front 
of  the  shoulder  to  be  inserted  into  the  radial  tubercle  of  the  humerus  on  its  ventral  aspect 
between  the  deltoid  and  the  coraco-brachialis.  Below  this  the  tendon  is  continued  by  two 


IIS  SCHULTE,  SEI  WHALE. 

very  strong  ligamentous  bands;  the  larger  is.  continued  in  the  line  of  the  tendon  along  the 
venter  of  the  humerus  to  the  capsule  of  the  elbow  joint  and  the  proximal  portion  of  the  radius; 
the  smaller  takes  a  slightly  oblique  course  to  the  ulnar  aspect  of  the  elbow  passing  laterad  of  the 
insertion  of  the  coraco-brachialis,  latissimus  and  teres.  In  these  bands  it  is  possible  to  see  the 
rudiments  of  the  long  and  short  heads  of  the  biceps.  Carte  and  McAlister  mention  tendinous 
bands  on  the  flexor  surface  of  the  humerus  in  B.  rostrata  (—  B.  acuto-rostrata) ,  which  they  too 
take  to  be  rudiments  of  the  biceps.  For  the  rest  their  account  of  the  muscules  of  this  group 
differs  materially  from  the  foregoing.  They  describe  a  masto-humeral  with  additional  origins 
from  the  transverse  processes  of  the  anterior  cervical  vertebrae.  This  they  found  inserting 
into  the  anterior  and  internal  part  of  the  humerus.  They  do  not  mention  a  trapezius  (cephalo- 
humeralis)  nor  a  cleido-mastoid.  Their  sterno-mastoid  has  an  additional  head  from  the  first 
and  second  costal  cartilages.  This  last  point  of  difference  is  probably  due  to  their  failure  to 
distinguish  the  sterno-mandibularis  which  in  B.  borealis  has  a  costal  origin  and  immediately 
overlies  the  sterno-mastoid. 

Ventro-appendicular  musculature. —  The  pectoralis  is  an  extensive  sheet  of  muscle  which 
covers  the  venter  of  the  thorax  and  extends  upon  the  abdomen  to  within  1.5  cm.  of  the  umbili- 
cus. It  arises  from  the  ventral  surface  of  the  sternum,  from  the  whole  width  of  the  first  rib 
by  a  narrow  origin  between  the  attachments  of  the  rectus  and  of  the  external  oblique,  and 
extensively  from  the  linea  alba.  Here  while  it  approaches  its  fellow  of  the  opposite  side  very 
closely,  I  was  not  able  to  detect  an  interdigitation  of  the  fasciculi  of  the  two  muscules.  The 
fasciculi  are  directed  in  the  main  transversely  with  a  slight  inclination  cephalad  to  an  exten- 
sive insertion  into  the  lateral  raphe"  and  the  aponeurosis  which  invests  the  humerus,  only  a 
minority  of  its  fasciculi  inserting  into  the  preaxial  border  of  that  bone  under  cover  of  the 
deltoid.  In  the  raphe  the  pectoralis  is  united  with  the  ventral  and  dorsal  divisions  of  the  pan- 
niculus  and  with  the  latissimus  dorsi,  and  retains  this  relation  to  the  ventral  panniculus  in  its 
insertion  into  the  aponeurosis  of  the  arm.  Its  pannicular  affinities  are  further  indicated  by  its 
innervation  from  branches  of  the  long  thoracic.  Throughout  the  whole  sheet  the  course  of 
the  fasciculi  are  parallel,  there  is  no  convergence  towards  the  shoulder,  and  the  thoracic  portion 
of  the  muscle  is  distinguished  from  the  abdominal  by  its  greater  thickness  alone.  There  is 
no  pectoralis  minor. 

The  latissimus  dorsi  is  a  small  thin  muscle  parallel  to  the  caudal  margin  of  the  scapula. 
It  arises  from  the  aponeurosis  covering  the  dorsal  extensor  muscles  and  on  its  deep  surface  it 
is  reinforced  by  delicate  slips  from  the  7th,  8th  and  9th  ribs.  Its  fasciculi  converge  somewhat 
to  their  insertion  being  directed  rostro-ventrad  to  the  lateral  raphe  where  they  meet  those  of 
the  pectoralis,  and  to  the  flexor  surface  of  the  humerus  where  they  are  inserted  ventral  to  the 
subscapularis  and  teres.  With  the  tendon  of  the  last  the  latissimus  is  intimately  joined  as  it 
crosses  its  ventral  surface  to  gain  a  proximal  insertion  upon  the  humerus.  The  nerve  supply 
is  by  a  slender  branch  of  the  long  thoracic  which  lies  upon  the  ental  surface  of  the  muscle  and 
penetrates  it  near  its  middle. 

The  coraco-brachialis  is  placed  on  the  ventro-mesial  aspect  of  the  shoulder.  It  arises 
from  the  tip  of  the  coracoid  process  and  crossing  the  tendon  of  the  subscapularis  is  inserted  into 
the  humerus  immediately  below  the  head  and  just  mesial  to  the  ligamentous  bands,  which  are 
probably  representative  of  the  biceps,  with  the  postaxial  one  of  which  it  is  connected  by  a  narrow 
slip  as  Perrin  found. 


PLATE  XLV. 


PLATE  XLV. 


Fig.  1. 
Fig.  2. 


Balcenoptera  borealis. 

Musculature  of  flipper,  mesal  view.     2f  X  natural  size. 
Skeleton  of  flipper,  mesal  view  showing  attachments  of  muscles. 


24  X  natural  size. 


1.  M.  rhomboideus. 

2.  M.  levator  anguli  scapula. 

3.  M.  omohyoideus. 

4.  M.  subscapularis. 

5.  M.  teres  major. 

6.  M.  serratus  anticus. 

7.  M.  supraspinatus. 

8.  Processus  coracoideus. 

9.  M.  coraco-brachialis. 


10.  M.  masto-humeralis. 

11.  M.  deltoideus. 

12.  Mm.  pectoralis  and  latissimus  dorsi 

13.  M.  triceps. 

14.  Ligamentous  bands  representative  of  biceps. 

15.  M.  flexor  communis  digitorum. 

16.  M.  flexor  radialis. 

17.  M.  flexor  ulnaris. 


Memoirs  Am.  Mus.  Nat.  Hist. 


N.  S.,  Vol.  I,  Plate  XLV. 


fc— • 


13 


17 


F is-    I. 


16 


Fig.  2. 


BALyENOPTERA    BOREALIS. 


SCHULTE,  SEI  WHALE.  419 

The  long  head  of  the  triceps  arises  from  the  caudal  extremity  of  the  glenoid  cavity,  the 
glenoid  ligament  and  capsule  of  the  shoulder  joint.  The  belly  is  broad  and  flat  and  rrarkcdly 
convex  along  its  dorsal  margin.  It  is  inserted  by  a  short  tendon  into  the  extremity  of  the  long 
olecranon  process.  The  external  head,  triangular  in  shape,  arises  from  the  postaxial  border 
of  the  humerus  in  its  distal  half.  Its  fasciculi  are  inserted  into  the  whole  length  of  the  cephalic 
border  of  the  olecranon  save  for  the  area  at  the  tip  occupied  by  the  long  head.  The  third  head 
I  failed  to  find.  Its  presence  is  recorded  in  B.  rostrata  by  Carte  and  McAlister.  Perrin  does 
not  describe  the  triceps  but  his  illustrations  show  only  a  long  and  an  external  head. 

Trachelo-costo-scapular  muscles. —  The  serratus  anticus  is  best  developed  at  the  caudal 
angle  of  the  scapula.  Here  strong  slips  from  the  4th,  5th  and  6th  ribs  converge  to  an  insertion 
at  the  angle  itself  and  the  adjacent  surface.  Except  in  this  region  I  failed  to  find  fasciculi  of 
this  muscle.  Carte  and  MacAlister  found  it  arising  from  the  eight  caudal  ribs  with  a  slip  from 
the  second.  Its  nerve  supply  is  from  the  long  thoracic  nerve. 

The  levator  anguli  scapulae  is  a  short  thick  muscle  arising  from  the  costal  process  of  the 
second  cervical  vertebra.  It  passes  between  the  scalenus  and  the  trachelo-mastoid  turning 
dorsad  to  be  inserted  into  the  ventral  aspect  of  the  cephalic  angle  of  the  scapula.  It  is  supplied 
by  ventral  branches  of  adjacent  cervical  nerves. 

Rhomboideus. —  The  rhomboideus  is  not  cleft  into  major  and  minor,  but  .forms  a  narrow  con- 
tinuous sheet  along  the  whole  length  of  the  suprascapula.  Its  origin  does  not  extend  to  the 
spines  of  the  vertebrae,  but  takes  place  by  muscular  fasciculi  from  the  dorsal  aponeurosis  over 
the  longissimus  dorsi. 

Scapula-humeral  muscles. —  The  deltoid  is  the  largest  of  this  group.  It  arises  from  the 
rostral  two  fifths  of  the  dorsum  scapulae  as  far  caudad  as  the  infraspinatus,  which  it  overlaps 
by  its  caudal  margin,  further  from  the  ectal  surface  and  ventral  border  of  the  acromion  process, 
and  from  the  fibrous' tissue,  which  bridges  the  angle  between  this  process  and  the  rostral  border 
of  the  scapula,  serving  as  an  intermuscular  septum  between  the  deltoid  and  the  supraspinatus. 
The  muscle  is  coarsely  fasciculated.  Its  bundles  converging  towards  the  head  of  the  humerus 
are  inserted  upon  a  tendon,  which  appears  first  on  the  surface  and  caudal  border  of  the  muscle. 
Into  this  the  fasciculi  of  acromial  origin  insert  along  its  preaxial  border  as  it  approaches  the 
humerus,  so  that  here  the  muscle  is  fleshy  to  its  insertion.  Some  of  these  fasciculi  reach  the 
radial  tuberosity  of  the  humerus  inserting  between  the  infraspinatus  dorsad  and  the  masto- 
humeral  and  supraspinatus  ventrad.  The  tendon  after  crossing  that  of  the  infraspinatus, 
which  separates  it  from  the  shoulder-joint,  is  inserted  into  dorsal  surface  of  the  humerus  from 
the  neck  distad  and  into  the  whole  preaxial  border  of  that  bone,  blending  distad  with  the  capsule 
of  the  elbow  and  extending  upon  the  radius,  and  above  expanding  into  the  deep  fascia,  of  the 
flexor  surface  of  the  arm. 

Perrin  describes  a  strengthening  band  of  the  capsule  of  the  shoulder  passing  from  the  glenoid 
margin  and  the  base  of  the  coracoid  to  the  humerus.  This  is  here  represented  by  a  small  sub- 
deltoid  muscle.  It  arises,  as  Perrin's  ligament  from  the  base  of  the  coracoid  and  the  margin 
of  the  glenoid  cavity,  but  is  much  narrower.  Its  tendon  rests  upon  the  capsule  of  the  shoulder 
joint  which  it  crosses  on  its  rostro-lateral  aspect  to  be  inserted  into  the  tuberosity  of  the  humorus 
under  cover  of  the  deltoid,  between  the  infraspinatus  and  the  fleshy  insertion  of  the  deltoid 
which  separate  it  from  the  cephalo-humeralis  and  supraspinatus.  Both  of  these  muscles  are 
supplied  by  the  circumflex  nerve. 


420  SCHULTE,  SEI  WHALE. 

The  supraspinatus,  covered  by  the  deltoid,  is  a  larger  muscle  and  of  more  extensive  origin 
than  in  the  porpoise  (Rapp,  Stannius)  and  yet  far  from  attaining  half  the  size  of  the  deltoid 
as  found  in  B.  rostrata  ( =  B.  acuto-rostrata)  by  Carte  and  MacAlister,  with  whose  description 
it  corresponds  in  general.  It  arises  from  the  rostral  border  of  the  scapula  as  far  ventrad  as  the 
acromion,  from  the  ventral  surface  of  the  acromion,  and  from  a  fibrous  layer,  which  closes  the 
angle  between  scapula  and  acromion  and  gives  origin  by  its  ectal  surface  to  the  deltoid.  The 
fasciculi  converge  to  a  tendon,  which  passing  upon  the  rostral  aspect  of  the  shoulder-joint  is 
inserted  into  the  radial  tuberosity  of  the  humerus  under  cover  of  the  tendon  of  the  masto- 
humeral.  It  is  supplied  by  the  suprascapular  nerve. 

The  infraspinatus  arises  from  the  vertebral  margin  of  the  scapula  in  its  third  and  fourth 
fifths  and  from  the  corresponding  portion  of  its  dorsum  as  far  as  the  neck.  The  muscle  is  tri- 
angular, abutting  upon  the  origin  of  the  teres  by  its  caudal  margin,  overlapped  by  the  deltoid 
along  its  rostral  border.  After  crossing  the  long  head  of  the  triceps  it  passes  into  a  flattened 
tendon,  applied  to  the  dorsum  of  the  shoulder-joint,  to  which  it  is  adherent,  then  expanding 
somewhat  it  is  inserted  into  the  radial  tuberosity  of  the  humerus  on  its  extensor  aspect.  At 
its  insertion  it  is  embraced  by  the  expansion  of  the  deltoid.  It  is  innervated  by  the  supra- 
scapular  nerve. 

The  teres  arises  from  two  thirds  of  the  caudal  border  of  the  scapula  adjacent  to  the  neck 
and  from  a  firm  intermuscular  septum  common  to  it  and  the  subscapularis.  Its  tendon  crosses 
that  of  the  latissimus  dorsi  very  obliquely  being  intimately  united  with  its  dorsal  surface,  and  is 
then  inserted  into  the  shaft  of  the  humerus  distal  to  the  subscapularis.  Its  nerve  is  derived 
from  the  long  thoracic  in  its  course  through  the  axilla. 

The  subscapularis  occupies  the  whole  venter  of  the  scapula.  It  is  partially  divided  at  its 
origin  into  eight  fleshy  slips.  Its  fasciculi  converge  to  a  narrow  insertion  upon  the  postaxial 
surface  of  the  humerus  immediately  below  the  head,  and  by  an  aponeurotic  expansion  into  the 
fascia  of  the  flexor  surface  of  the  arm.  It  is  supplied  by  small  branches  of  the  long  thoracic. 
Its  tendon  is  firmly  united  with  the  capsule  of  the  shoulder,  not  perforating  it  as  Carte  and 
MacAlister  describe,  but  can  be  separated  leaving  the  joint  intact,  in  this  corresponding  with 
the  observations  of  Perrin. 

Intrinsic  muscles  of  the  flipper. —  The  extensor  communis  digitorum  arises  from  the  capsule 
of  the  elbow-joint  and  from  the  adjacent  surfaces  of  the  ulna  and  radius  together  with  their 
interosseus  membrane.  The  ulnar  origin  is  small  being  confined  to  3  or  4  mm.  of  the  proxi- 
mal portion  of  the  bone.  On  the  radius  the  origin  includes  the  proximal  three  fifths  of  the 
shaft.  The  tendon  appears  first  at  the  ulnar  border  of  the  belly  and  before  the  carpus  is  reached 
has  received  all  the  fasciculi  of  the  muscle.  On  the  carpus  the  tendon  expands  and  divides  into 
four  slips.  The  middle  two  follow  the  axial  lines  of  the  two  middle  digits.  The  postaxial  slip 
follows  the  preaxial  border  of  the  ulnar  digit;  the  preaxial  slip  the  postaxial  border  of  the  radial 
digit.  In  their  whole  length  these  tendons  are  united  by  fibrous  tissue  to  the  perichondrium 
of  the  phalanges  and  the  union  is  especially  firm  at  the  enlarged  interphalangeal  joints.  I 
could  not  make  out  the  definite  lateral  slips  in  the  region  of  the  joints,  which  Struthers  ]  mentions 
in  his  beautiful  description  and  illustration  of  this  muscle  in  B.  musculus  ( =  B.  phy solus),  and 
which  Carte  and  MacAlister  describe  in  B.  rostrata  (  =  B.  acuto-rostrata).  From  the  diminutive 


1  Struthers,  1871.     Op.  cit.,  Jour.  Anat,  and  Phys.,  Vol.  VI,  p.  107. 


PLATE  XLVI. 


PLATE  XLVI. 


Bakenoptera  borealis. 

Fig.  1.     Skeleton  of  flipper,  lateral  view  showing  attachments  of  muscles.     2f  X  natural  size. 
Fig.  2.     Suprahyoid  and  infrahyoid  muscles.     Natural  size. 


1.  M.  deltoideus,  origin. 

2.  M.  supraspinatus,  origin. 

3.  M.  infraspinatus,  origin. 

4.  M.  teres  major,  origin. 

5.  M.  subdeltoideus,  origin. 

6.  M.  coraco-brachialis,  origin. 

7.  M.  subdeltoideus,  insertion. 

8.  M.  infraspinatus,  insertion. 

9.  M.  deltoideus,  insertion. 

10.  M.  triceps,  origin  of  long  head. 

11.  M.  triceps,  insertion  of  long  head. 

12.  M.  triceps,  origin  of  short  head. 

13.  M.  triceps,  insertion  of  short  head. 

14.  M.  flexor  ulnaris,  origin. 

15.  M.  flexor  ulnaris,  insertion. 

16.  M.  extensor  digitorum  communis. 

17.  Longitudinal  stratum  of  musculature  of  ventral  pouch. 


18.  M.  sternomandibularis. 

19.  N.  hypoglossus. 

20.  N.  lingualis. 

21.  M.  genioglossus. 

22.  M.  depressor  mandibulse. 

23.  M.  hyoglossus. 

24.  Os  hyoides. 

26.  M.  omohyoideus. 

26.  M.  sternohyoideus. 

27  M.  sternothyroideus. 

28.  M.  thyrohyoideus. 

29.  M.  sterno-mastoideus. 

30.  M.  pectoralis. 

31.  M.  scalenus. 

32.  M.  obliquus  externus. 

33.  M.  rectus  abdominis. 

34.  M.  sternomandibularis,  costal  origin. 


Memoirs  Am.  Mus.  Xat,  Hist. 


N.  S.,  Vol.  I,  Plate  XLVI. 


Fig.  1. 


20 


31 


Kg.  2. 
BAL/KNOPTERA  BOREALIS. 


SCHULTE,  SEI  WHALE.  421 

proportions  of  these  structures  in  this  foetus  I  doubt  if  they  could  be  seen  without  recourse 
to  sections.  In  Perrin's  specimen  the  origin  extended  proximad  upon  the  humerus,  and  the 
tendon  of  digit  II  gave  off  a  slip  to  the  metacarpus.  This  I  could  not  find,  nor  does  Struthers 
mention  its  presence  as  a  distinct  element  in  B.  musculus  (=  B.  physalus),  but  finds  all  the 
tendons  united  to  the  metacarpals  in  the  same  way  as  to  the  phalanges. 

The  flexor  carpi  ulnaris  arises  from  the  distal  margin  of  the  olecranon  and  from  the  adjacent 
shaft  of  the  ulna  to  a  slight  extent.  Its  fasciculi  converge  to  a  long  and  slender  tendon  which 
is  inserted  into  the  pisiform.  It  is  identically  the  same  as  in  B.  musculus  (Struthers)  but  differs 
in  its  insertion  from  B.  rostrata  ( =  B.  acuto-rostrata)  where  Carte  and  MacAlister  found  it 
inserting  into  the  fourth  metacarpal,  Perrin  into  the  ulna. 

The  flexor  digitorum  radialis  is  a  slender  muscle  arising  from  the  postaxial  portion  of  the 
shaft  of  the  radius  as  far  distad  as  the  middle  of  the  bone,  from  the  interosseous  ligament,  and 
from  the  septum  between  it  and  the  flexor  ulnaris.  Its  tendon  runs  distad  and  towards  the  radial 
digit  where  it  joins  the  slip  of  the  flexor  ulnaris  to  that  digit. 

The  flexor  digitorum  ulnaris  arises  from  the  internal  epicondyle  of  the  humerus,  the  cap- 
sule of  the  elbow  joint,  the  shaft  of  the  ulna  in  its  proximal  half,  the  interosseus  membrane 
and  the  intermuscular  septum  common  to  it  and  the  flexor  radialis.  Its  fasciculi  converge  upon 
a  slender  tendon  which  upon  reaching  the  carpus  divides  into  four  slips.  These  are  continued 
upon  the  flexor  surface  of  the  phalanges  to  the  last.  In  this  course  the  tendons  are  firmly  bound 
down  to  the  phalanges  and  especially  to  the  enlarged  interphalangeal  synchondroses,  in  the 
last  position  by  expansions  of  the  tendon  which  are  attached  to  the  sides  of  the  articular  carti- 
lages. The  slip  to  digit  IV  continues  the  line  of  the  main  tendon,  that  to  digit  V  is  the  strong- 
est of  the  four.  The  slip  to  digit  II  is  of  approximately  the  same  size,  certainly  not  larger  than 
those  to  digits  III  and  IV.  I  could  find  no  trace  of  a  palmaris  longus  described  by  Carte  and 
MacAlister,  nor  of  the  flexor  sublimis  found  by  Perrin,  in  B.  rostrata  (=  B.  acuto-rostrata).  In 
this  as  in  other  respects  the  intrinsic  muscles  of  the  flipper  agree  closely  with  the  conditions 
in  B.  musculus  (=  B.  physalus)  as  recorded  by  Struthers. 

Abdominal  muscles. —  The  rectus  abdominis  is  a  broad  and  massive  muscle,  forming  the 
chief  support  of  the  abdominal  wall  and  extending  from  the  sternum  to  the  pelvis  as  a  con- 
tinuous sheet  uninterrupted  by  tendinous  inscriptions.  It  arises  from  the  ventral  surface  of 
the  sternum  and  the  whole  breadth  of  its  caudal  margin,  and  from  the  ventral  extremities  of 
the  first  eight  ribs  and  their  cartilaginous  prolongations.  The  costal  slips  diminish  in  size  caudad. 
Those  from  the  second  and  following  ribs  arise  from  their  caudal  borders  and  add  themselves  to 
the  lateral  border  and  deep  surface  of  the  muscle,  which  thus  increases  in  breadth  as  well  as 
thickness  in  its  thoracic  portion.  It  attains  its  maximum  width  a  little  rostrad  of  the  umbili- 
cus and  thence  contracts  again  caudad.  As  it  approaches  the  pelvis  the  rectus  divides  into  a 
medial  and  a  lateral  portion  separated  by  a  large  neurovascular  foramen,  through  which  emerge 
the  nerves  and  blood  vessels  for  the  genitalia  and  proximal  portion  of  the  pedicle.  The  median 
division  of  the  muscle  is  narrow  and  inserts  in  large  part  upon  the  rostral  border  and  ectal  surface 
of  the  ilium.  The  remainder  expands  into  an  aponeurosis  interposed  between  the  ischio-caudalis 
and  the  hypaxial  muscle,  which  inclining  mesad  joins  with  its  antimere  by  its  more  rostral 
fibres,  forming  an  arch  to  give  passage  to  the  rectum  and  vagina,  while  its  more  caudal  fibres 
are  attached  to  the  proximal  chevron  bones  in  common  with  similar  fibres  from  the  opposite 
side.  The  lateral  division  of  the  aponeurosis  expands  beneath  the  obliquus  internus  and  pan- 


SCHULTE,  SET  WHALE. 

niculus  and  can  be  followed  to  the  lateral  septum  ventral  to  the  transversarius,  through  which 
it  gains  attachment  to  the  transverse  processes  of  the  caudal  vertebrae.  A  muscular  slip  from 
the  dorsal  division  passes  at  the  lateral  margin  of  the  neuro-muscular  foramen,  intervening 
between  it  and  a  weak  area  in  the  dorsal  aponeurosis,  to  be  inserted  upon  the  ventral  tendi- 
nous expansion.  Near  this  point  of  insertion,  which  is  just  caudal  to  the  ischium,  a  small  trans- 
verse muscle  arises  and  passing  mesad  is  inserted  into  the  fibrous  tissue  of  the  midventral  line, 
in  common  with  its  antimere,  between  the  anus  and  the  first  chevron  bone.  It  is  possible  to 
see  in  this  the  representative  of  the  coccygeus. 

The  rectus  is  enclosed  in  a  strong  sheath  derived  from  the  aponeurosis  of  the  obliqui  and 
transversalis.  It  is  weak  in  the  thoracic  region  and  here  adheres  to  the  venter  and  dorsum 
of  the  muscle  so  firmly  as  to  be  removed  with  difficulty.  The  aponeurosis  of  the  external  oblique 
forms  the  more  ventral  layer  of  the  sheath;  that  of  the  internal  oblique  splits  to  enclose  the 
rectus,  and  this  cleft  involves  the  muscular  fasciculi  as  well  as  the  aponeurotic  lamellae,  while 
the  aponeurosis  of  the  transversalis  forms  the  ental  layer  passing  wholly  upon  the  dorsum  of 
the  rectus.  These  several  layers  fuse  in  the  midventral  line  to  form  the  linea  alba,  which  is 
narrow  and  weak  in  the  thoracic  region  becoming  firm  and  dense  in  the  abdomen.  At  the 
umbilicus  the  dorsal  and  ventral  layers  of  the  sheath  are  continuous  around  the  mesal  margin 
of  the  rectus,  and  are  separated  from  those  of  the  opposite  side  by  an  interval  which  gives 
passage  to  the  umbilical  cord.  Here  the  connective  tissue  structures  are  very  much  thickened. 

The  obliquus  externus,  except  upon  the  front  of  the  thorax,  is  an  extremely  thin  sheet. 
It  arises  by  a  series  of  digitations  from  all  the  ribs  and  beyond  these  from  the  lumbar  aponeurosis, 
but  here  only  to  a  very  small  degree,  so  that  a  considerable  portion  of  the  internal  oblique  is 
left  exposed.  The  slip  from  the  first  rib  is  massive  and  is  attached  to  its  ectal  surface  as  well 
as  its  caudal  border  abutting  upon  the  insertion  of  the  scalenus  anticus,  from  which  however 
it  is  clearly  separated.  The  remaining  digitations  are  attached  to  the  caudal  margins  of  the 
ribs  at  successively  greater  distances  from  the  median  line.  Those  arising  from  the  second, 
third  and  fourth  ribs  interdigitate  with  the  scalenus  medius,  but  I  could  not  find  that  any  fasci- 
culi were  continuous  from  one  muscle  to  the  other  as  Carte  and  MacAlister  observed  in  B. 
rostrata  ( =  B.  acuto-rostrata).  The  slips  from  the  fifth  and  sixth  ribs  interlock  with  slips  of  the 
serratus  anticus.  The  fasciculi  are  directed  very  obliquely  caudad  and  mesad.  They  are 
continued  a  short  distance  upon  the  venter  of  the  rectus  before  becoming  aponeurotic,  except 
at  the  caudal  end  of  the  muscle  where  they  terminate  before  reaching  the  rectus. 

The  obliquus  internus  is  considerably  thicker  than  the  externus.  It  arises  from  the  lum- 
bar aponeurosis  as  far  caudad  as  the  transverse  plane  of  the  vulva.  Its  fasciculi  are  directed 
very  obliquely  rostrad  and  ventrad.  At  the  margin  of  the  rectus  it  divides  into  two  lamellae. 
The  superficial  promptly  becomes  aponeurotic  and  is  thus  inserted  into  the  linea  alba.  The 
more  caudal  of  the  fasciculi  of  the  deep  lamella  behave  in  a  similar  manner  upon  the  dorsum 
of  the  rectus  muscle,  the  more  rostral  are  inserted  upon  the  caudal  margins  of  the  cartilages  of 
the  last  seven  ribs,  close  to  the  slips  of  origin  of  the  rectus. 

The  transversalis,  arising  likewise  from  the  lumbar  aponeurosis  and  for  about  the  same 
extent  as  the  obliquus  internus,  is  directed  transversely  towards  the  median  line,  its  aponeuro- 
sis passing  wholly  dorsal  to  the  rectus.  The  sheet  is  continued  in  the  thoracic  region  by  slips 
from  the  deep  surface  of  the  extremities  of  the  last  nine  ribs,  interdigitating  with  the  origins  of 
the  diaphragm.  Like  the  external  oblique  this  layer  is  very  thin. 


PLATE  XLVII. 


PLATE  XLVII. 


Balcenoptera  borcalis. 

Fig.  1.     Deep  muscles  of  thorax  and  abdomen,  dorsal  musculature.     J  X  natural  size. 
Fig.  2.     Situs  viscerum,  and  hypaxial  muscle  of  pedicle,     f  X  natural  size. 


1.  M.  semispinalis  capitis. 

2.  M.  longissimus  dorsi. 

3.  M.  iliocostalis. 

4.  M.  splenius. 

5.  M.  trachelo-mastoideus. 

6.  M.  transversarius. 

7.  M.  levator  anguli  scapula. 

8.  M.  sternomastoideus  and  mastohumeralis. 

9.  M.  scalenus. 

10.  M.  transversalis  abdominis. 

11.  M.  rectus. 

12.  M.  coccygeus. 

13.  M.  temporalis. 

14.  M.  masseter,  pars  superficialis. 

15.  M.  masseter,  pars  profunda. 

16.  M.  depressor  mandibulse. 

17.  Hypaxial  muscle  of  pedicle,  superficial  portion. 

18.  The  same,  lateral  portion. 

19.  The  same,  mesal  portion. 

20.  Thymus. 

21.  Pulmonary  artery. 

22.  Left  atrium. 


23.  Left  ventricle. 

24.  Lung. 

25.  Liver. 

26.  Falciform  ligament. 

27.  Omentum. 

28.  Stomach,  second  compartment. 

29.  Small  intestines. 

30.  Rib  XIII. 

31.  Kidney. 

32.  Ovary. 

33.  Ureter. 

34.  Bladder. 

35.  Urethra. 

36.  Vagina. 

37.  Rectum. 

38.  Umbilical  artery. 

39.  Colon. 

40.  Diaphragm. 

41.  First  thoracic  rib. 

42.  Cervical  rib  fused  with  the  foregoing. 

43.  M.  sternothyroideus. 

44.  M.  thyrohyoideus. 


Memoirs  Am.  Mus.  Xat.  Hist. 


N.  S.,  Vol.  I,  Plate  XLVII. 


Si  to 


02 

hH 
iJ 


SCHULTE,  SKI  WHALK.  423 

Pelvic  musculature. —  The  ischio-caudalis  arises  from  the  ectal  surface  of  the  pelvis  in  its 
ischial  portion  by  its  mesal  fasciculi,  and  far  more  extensively  from  the  sheath  of  the  rectus 
lateral  to  the  pelvis.  It  is  a  thin  sheet-like  muscle  of  triangular  form,  united  in  the  midline 
with  its  fellow  of  the  opposite  side  by  a  narrow  raphe.  Its  fasciculi  are  directed  caudad  and 
mesad  and  are  inserted  into  the  tips  of  the  chevron  bones.  The  muscle  extends  to  the  junction 
of  the  pedicle  with  the  flukes,  being  the  most  superficial  of  the  ventral  muscles  of  the  region 
and  covered  only  by  the  aponeurosis  which  continues  the  panniculus.  The  muscles  are  united 
as  far  rostrad  as  the  anus,  where  they  diverge  to  give  passage  to  the  rectum.  On  its  dorsum  as 
in  Phoccena  (Stannius)  they  are  united  by  a  firm  aponeurosis. 

The  levator  ani  arises  from  the  ental  surface  of  the  pelvis  and,  caudal  to  the  ischium,  its 
origin  is  continued  from  the  deep  surface  and  mesal  border  of  the  ischio-caudalis  to  which  it 
is  united  by  a  tendinous  inscription.  Its  fasciculi  pass  to  the  midline  almost  transversely  unit- 
ing in  a  raphe  with  those  of  their  antimere;  where  passage  is  given  to  the  vagina  and  rectum, 
the  bundles  of  the  levator  are  continued  into  their  walls. 

The  ischio-cavernosus  is  a  relatively  large  muscle,  superficial  to  the  levator.  It  arises 
from  the  mesal  margin  of  the  ischium  and  expanding  slightly  is  inserted  into  the  dorsum  of 
the  clitoris,  uniting  with  its  fellow  in  a  raphe. 

Intercostals. —  These  muscles,  of  which  there  are  twelve  pairs  on  each  side,  were  strongly 
developed  and  characterized  by  the  marked  obliquity  of  their  fasciculi.  In  other  respects 
their  arrangement  was  as  usual.  The  interval  between  the  two  proximal  segments  of  the  bifur- 
cated first  rib  was  occupied  by  mucle  continuous  with  and  having  the  direction  of  the  scalenus. 

Diaphragm. —  This  is  a  strong  and  compactly  built  muscle,  in  its  sterno-costal  portion 
averaging  somewhat  more  than  1  mm.  in  thickness.  On  its  abdominal  surface  is  a  dense  end- 
abdominal  fascia,  upon  which  is  a  heavy  layer  of  subperitoneal  areolar  tissue,  the  whole,  dia- 
phragm, fascia  and  areolar  tissue  measuring  2  mm.  in  thickness.  The  diaphragm  in  the  ventral 
midline  arises  from  the  linea  alba  and  the  ental  layer  of  the  sheath  of  the  rectus  between  the 
extremities  of  the  ribs  of  the  sixth  pair.  These  fasciculi,  the  equivalent  of  the  pars  sternalis, 
have  a  sagittal  course  and  overlap  the  bundles  of  the  pars  costalis  on  their  abdominal  surface 
so  that  there  is  no  fibrous  interval  between  these  portions  of  the  muscle.  The  pars  costalis 
arises  along  an  oblique  line  extending  from  the  tip  of  the  sixth  to  that  of  the  thirteenth  rib. 
Here  it  turns  upon  itself  and  the  line  of  origin  is  continued  in  a  dorso-rostral  direction  along 
the  ental  surface  and  upper  border  of  the  last  rib  for  the  distal  third  of  its  length.  These  fasci- 
culi are  directed  rostrad  and  dorsad  having  nearly  the  same  inclination  as  the  ribs  from  which 
they  arise,  in  this  direction  agreeing  with  the  lateral  bundles  of  the  pars  lumbalis  with  which 
they  are  perfectly  continuous.  The  pars  lumbalis  is  composed  of  a  crus  laterale,  crus  inter- 
medium and  crus  mediale.  The  latter  arises  tendinous  from  the  bodies  of  the  first  two  lumbar 
vertebrae.  The  tendon  of  origin  arches  in  front  of  the  aorta  immediately  rostrad  of  the  coeliac 
axis.  From  this  in  its  whole  length  arise  fasciculi  of  a  general  sagittal  direction  and,  with  refer- 
ence to  the  crus  intermedium,  of  superficial  position.  The  bundles  of  the  right  crus  are  com- 
pacted into  a  ridge  as  they  ascend  and  arch  ventrad  of  the  orificium  oesophagi,  forming  a  sharp 
muscular  falx  to  the  right  and  in  front  of  the  aperture.  Those  of  the  left  crus  continue  as  a 
flattened  band  upon  the  dorsum  of  the  oesophagus  and  turning  to  the  right  reach  the  central 
tendon.  The  remainder  of  the  diaphragm  arises  from  the  sheath  of  the  great  hypaxial  muscle, 
which  extends  from  the  last  rib  throughout  the  lumbar  region  and  the  pedicle.  The  line  of 


424  SCHULTE,  SEI  WHALK. 

origin  has  here  the  shape  of  an  inverted  V  with  unequal  arms.  The  longer  lateral  arm  gives 
rise  to  the  crus  laterale,  the  mesal  to  the  crus  intermedium,  but  only  in  part  for  bundles  of  this 
portion  arise  also  from  the  deep  surface  of  the  crus  mediale.  The  lateral  crus  is  continuous  with 
the  pars  costalis  and  has  the  same  orientation  of  its  bundles.  It  is  separated  from  the  crus 
intermedium  by  a  fibrous  trigone,  which  cephalad  has  its  apex  prolonged  into  a  strand,  which 
receives  on  its  lateral  aspect  the  rostro-mesally  directed  bundles  of  the  crus  laterale,  on  its  mesal 
side  the  fasciculi  of  the  intermediate  crus,  which  have  a  rostro-lateral  inclination.  On  the  right- 
side  the  strand  proceeding  from  the  fibrous  triangle  joins  the  centrum  tendineum,  on  the  left 
it  is  possible  to  follow  it  beside  the  oesophageal  orifice,  where  it  turns  towards  the  right  as  though 
to  join  the  central  tendon  by  arching  between  the  orificium  oesophagi  and  the  foramen  quad- 
rangulare,  but  here  its  course  is  obscured  by  muscular  bundles  and  it  disappears  from  view. 

The  centrum  tendineum  is  large,  but  is  confined  to  the  dorsal  plane  of  the  diaphragm.  Its 
most  ventral  point  is  the  caval  aperture  which  it  surrounds  with  a  narrow  zone  of  fibrous  tissue, 
expanding  caudad  in  a  wide  oval  which  exceeds  on  the  right  the  limits  of  the  hepatic  adhesion 
and  then  tapering  is  continued  by  the  fibrous  strand  already  described  to  the  trigone  of  the  right 
side.  On  the  left  the  margin  of  the  tendon  approaches  the  right  mesal  crus,  but  a  narrow  strip 
of  the  crus  intermedium  intervenes  between  them.  Thus  the  right  leaf  of  the  central  tendon 
is  highly  developed,  the  central  leaflet  is  all  but  entirely  replaced  by  muscle,  and  the  right  is 
represented  by  a  slight  expansion  in  the  fibrous  interval  between  the  crus  intermedium  and 
crus  laterale.  By  means  of  this  structure  on  the  right  the  central  tendon  is  prolonged  to  the 
origin  of  the  pars  lumbalis.  The  structure  of  the  muscle  is  peculiar  chiefly  as  a  consequence 
of  the  arrangement  of  its  fibrous  tissue.  This  as  a  whole  may  be  schematized  as  an  inverted 
U  with  its  ends  at  the  fibrous  trigones  and  its  arch,  obscured  it  is  true,  ventral  to  the  foramen 
cesophagi.  Into  the  ectal  contour  of  this  U  are  inserted,  converging  from  the  costal  arch,  the 
bundles  of  the  pars  costalis  and  caudad  also  those  of  the  crus  laterale.  More  superficially  and 
partly  overlapping  the  most  ventral  fasciculi  of  the  costal  portion,  the  sagittally  directed  pars 
sternalis  inserts  upon  the  arch  of  the  U.  The  crus  laterale,  the  origin  of  which  extends  upon 
the  tendinous  arch  of  the  crus  mediale,  inserts  upon  the  sides  of  the  ental  contour  of  the  U, 
while  the  crus  mediale,  itself  superficially  placed,  is  inserted  into  its  arch,  the  right  pillar  passing 
ventrad,  the  left  dorsad  to  the  oesophagus  and  blending  at  their  insertion.  As  a  result  of  the 
approximation  of  the  two  superficial  sets  of  bundles,  the  pars  sternalis  and  the  crura  medialia, 
the  tendinous  insertion  is  concealed  from  view,  and  the  arch  of  the  U  of  our  schema  is  buried  in 
the  substance  of  the  muscle. 

The  phrenic  nerves,  derived  chiefly  from  the  fourth  cervical,  emerge  from  the  scalenus 
near  its  mesal  border  and  passing  round  this  margin  descend  into  the  thorax  along  the  venter 
of  the  precava.  Here  the  nerve  of  the  left  side  receives  a  considerable  branch  from  the  fifth 
cervical.  After  passing  the  hila  of  the  lungs  the  nerves  are  concealed  in  the  accumulation  of 
subpleural  fat  about  the  pericardium.  They  enter  the  diaphragm  after  division  into  several 
branches.  The  inferior  phrenic  arteries  are  derived  from  the  aorta  caudad  of  the  origin  of 
the  superior  mesenteric.  Before  piercing  the  crus  mediale  each  gives  a  branch  to  the  adrenal. 
The  phrenic  veins  empty  into  the  renals. 

The  hypaxial  musculature. — •  The  muscles  placed  upon  the  ventral  surface  of  the  spine  attain 
an  extraordinary  and  highly  specialized  development  in  Balcenoptera.  They  extend  along  the 
whole  axis  in  this  position,  save  for  a  thoracic  interval  from  the  VI  to  the  XIII  dorsal  vertebra 


PLATE  XLVIII. 


PLATE  XLVIII. 


Baltmoptera  boredis. 


Fig.  1 .     Thoracic,  abdominal  and  pelvic  muscles,     f  natural  size. 

Fig  2      Suboccipital  muscles,    f  natural  size. 

Fig.  3.     Scalenus,  rectus  capitis  anticus  and  pterygoid  muse 

27. 
28. 
29. 


1.  External  auditory  meatus. 

2.  Temporo-maxillary  fibro-cartilage. 

3.  M.  hyoglossus. 

4.  M.  genioglossus. 

5.  M.  depressor  mandibulse. 

6.  M.  omohyoideus. 

7.  M.  thyrohyoideus. 

8.  M.  sternothyroideus. 

9.  M.  sternohyoideus. 

10.  M.  stemomastoideus. 

11.  M.  splenius. 

12.  M.  trachelomastoideus. 

13.  M.  levator  anguli  scapula. 

14.  M.  scalenus. 

15.  M.  strenomandibularis. 

16.  M.  serratus  anticus. 

17.  M.  serratus  posticus  inferior. 

18.  M.  obliquus  externus. 

19.  M.  obliquus  internus. 

20.  M.  rectus  abdominis. 

21.  M.  ischio  cavernosus. 

22.  M.  levator  ani. 

23.  M.  ischio-caudalis. 

24.  Pelvis. 

25.  Mm.  recti  capitis  postici. 

26.  M.  trachelo-occipitalis. 


f  natural  size. 

M.  obliquus  superior. 

M.  rectus  capitis  lateralis. 

Mm.  intertransversales  posteriores. 

30.  M.  multifidus. 

31.  M.  pterygoideus  internus. 

32.  M.  pterygoideus  externus. 

33.  Meckel's  cartilage. 

34.  Posterior  nares. 

35.  Zygoma. 

36.  Zygomatic  process  of  temporal  bone. 

37.  Postglenoid  process  of  temporal  bone. 

38.  Internal  maxillary  artery. 

39.  M.  stemomastoideus. 

40.  M.  mastohumeralis. 

41.  M.  depressor  mandibute. 

42.  Auditory  bulla. 

43.  External  auditory  meatus. 

44.  Facial  nerve. 

45.  Base  of  styloid. 

46.  Jugular  foramen. 

47.  M.  rectus  capitis  anticus  major. 

48.  M.  longus  colli. 

49.  First  rib. 

50.  Dome  of  pleura. 

51.  Aorta. 

52.  Transverse  process  of  axis. 


Memoirs  Am.  Mus.  Nat.  Hist. 


X.  S.,  Vol.  I,  Plate  XLVIII. 


IS  16 


:v 


30 


Fig.  2. 


RORTIAT.TS. 


SCHULTE,  SEI  WHALE.  425 

inclusive.  Thus  they  are  separated  into  two  districts,  that  of  the  neck  and  upper  thorax  and 
that  of  the  lumbar  region  and  pedicle.  In  the  neck  a  great  muscle  complex  is  formed,  in  which 
the  elements  of  the  lateral  group  (scalene)  are  very  imperfectly  differentiated  from  those  of  the 
mesal  (recti  antici  capitis).  The  complex  is  of  great  size  and  extends  its  insertion  far  upon  the 
basis  cranii,  as  well  as  its  origin  upon  the  ribs  and  spine.  From  these  two  sources  the  fasciculi 
converge  and  unite  inside  the  arch  of  the  first  rib,  thence  extending  as  a  single  mass  to  the  skull, 
so  that  the  whole  complex  has  the  form  of  an  inverted  Y,  the  diverging  arms  of  which  embrace 
the  dome  of  the  pleura  and  limit  its  extension  rostrad.  Carte  and  MacAlister  have  an  accurate 
description  of  this  muscle,  which  they  interpreted  as  "corresponding  to  the  longus  colli,  longus 
atlantis,  and  rectus  capitis  anticus  muscles,  and  in  part  also  to  the  scalenus  posticus  and  medius 
and  supracostal  muscles." 

The  lateral  portion  (scalene)  arises  broadly  from  the  ectal  surfaces  of  the  first  three  ribs, 
interdigitating  with  the  obliquus  externus,  and  by  narrower  slips  from  the  fourth  and  fifth  ribs, 
dorsal  to  the  origins  of  the  serratus  anticus.  The  fasciculi  from  the  latter  retain  a  measure  of 
independence  and  forming  the  dorsal  border  of  the  muscle,  ascend  to  the  extremities  of  the 
transverse  processes  of  the  cervical  vertebra?,  into  the  dorsal  aspects  of  which  they  are  inserted 
from  the  second  to  the  seventh  inclusive. 

They  thus  represent  a  highly  developed  and  partially  independent  scalenus  posticus.  The 
fasciculi  from  the  first  three  ribs  are  reinforced  laterally  by  a  portion  of  those  from  the  fourth 
and  fifth,  and  mesad  by  a  very  considerable  increment  from  the  ental  surface  of  the  first  rib. 
These  last  arise  from  the  region  of  the  bifurcation  ventrad  for  about  two  thirds  of  the  length 
of  the  rib  between  its  bifurcation  and  its  sternal  extremity,  and  occupy  this  surface  in  its  whole 
breadth.  Entally  they  rest  against  the  pleura.  They  seem  therefore  the  equivalent  of  the 
scalenus  minimus  of  human  anatomy.  In  their  ascent  to  the  spine  they  occupy  a  mesal  and 
caudal  position  in  the  scalene  mass,  so  as  to  reach  the  transverse  process  of  the  seventh  cervical 
vertebra.  They  are  however  incorporated  so  intimately  in  the  general  complex  that  they  can- 
not be  traced  as  a  separate  element,  and  many  of  them  extend  to  a  higher  level  in  company  with 
the  bundles  derived  from  the  first  three  ribs.  As  these  pass  dorsal  to  the  subclavian  vessels  they 
correspond  to  the  scalenus  medius,  the  anticus  being  absent.  The  insertion  is  into  the  ventral 
aspect  of  the  cervical  transverse  processes  close  to  their  tips,  and  in  common  with  the  rectus 
anticus  upon  the  basi-occipital,  occupying  with  reference  to  the  fasciculi  of  spinal  origin  a  lateral 
position  in  the  common  belly.  Near  the  first  rib  the  muscle  is  cleft  for  the  passage  of  the  nerves 
of  the  brachial  plexus,  those  of  the  cervical  piercing  it  separately  and  somewhat  laterad  as  well 
as  rostrad  to  the  brachial  hiatus.  It  is  innervated  by  short  branches  from  the  cervical  nerves 
as  they  pass  through  its  substance. 

The  mesal  group  falls  into  two  planes,  a  massive  superficial  portion  extending  from  the 
thoracic  vertebrae  to  the  basioccipital,  which  enters  into  relation  with  the  scalene,  and  which 
I  believe  is  better  interpreted  as  an  enormously  extended  rectus  anticus  major,  and  a  small 
deeper  stratum  confined  to  the  spine  and  having  the  arrangement  typical  of  the  longus  colli. 
In  addition  a  considerable  belly  arises  from  the  atlas  and  joins  the  deep  surface  of  the  belly  to 
the  occipital  bone;  this  seems  clearly  to  be  the  rectus  capitis  anticus  minor. 

The  superficial  stratum  arises  from  the  venter  and  sides  of  the  first  five  dorsal  vertebrae, 
extending  caudad  to  the  point  where  the  aorta  comes  into  contact  with  the  spine.  In  the  region 
of  the  upper  dorsal  and  last  cervical  vertebrae  it  receives  very  delicate  tendons  from  the  sides 


42(i  SCHULTE,  SEI  WHALE. 

of  the  vertebrae  well  dorsad,  towards  but  not  actually  from,  the  transverse  processes.  The  bulk 
of  its  fasciculi  arise  from  the  fifth,  fourth  and  third  dorsal  vertebrae  ventrally,  those  from  the 
sides  of  the  bodies  and  from  the  second  and  first  dorsals  form  but  a  small  fraction  of  the  belly. 
This  has  nearly  a  sagittal  course,  but  in  the  cervical  region  the  muscles  of  the  two  sides  diverge, 
again  converging  towards  the  occipital  so  that  an  oval  space  is  left  between  them  in  which  appears 
the  deeper  plane.  As  the  belly  ascends  in  the  neck  it  receives  laterally  the  scalene,  and  as  it 
passes  the  atlas  it  is  joined  by  a  short  thick  muscle  from  the  transverse  process  (rectus  capitis 
anticus  minor).  These  three  elements  are  blended  in  a  common  belly  which  inserts  into  the 
base  of  the  cranium  at  the  mesal  margin  of  the  auditory  bulla  as  far  rostrad  as  the  alae  of  the 
vomer.  Here  the  fasciculi  from  the  dorsal  vertebrae  extend  farthest  rostrad,  the  scalene  are 
laterad  and  for  the  most  part  at  the  caudal  margin  of  the  bulla,  the  rectus  minor  near  the  caudal 
margin  of  the  occipital. 

The  deeper  stratum  is  small  and  confined  to  the  spine.  Three  portions  can  be  distin- 
guished, one  longitudinal  and  two  oblique.  The  longitudinal  is  best  developed  and  extends  along 
the  ventral  common  ligament  of  the  vertebrae  from  the  third  dorsal  to  the  ventral  arch  of  the 
atlas,  arising  from  the  more  caudal  and  inserting  into  the  more  rostral  vertebrae.  The  majority 
of  its  fasciculi,  however,  reach  the  atlas.  The  caudal  oblique  portion,  arising  in  common  with 
the  longitudinal,  is  inserted  into  the  transverse  processes  of  the  fifth  and  sixth  cervical  vertebrae. 
The  rostral  oblique  portion  arises  from  the  transverse  processes  of  the  fifth  and  fourth,  and 
inserts  in  common  with  the  longitudinal  portion  into  the  atlas.  Thus  in  the  deep  plane,  which 
is  not  described  by  Carte  and  MacAlister,  we  find  a  perfectly  organized  longus  colli  independent 
of  the  superficial  stratum,  which  for  this  reason  seems  better  taken  as  the  representative  of  the 
rectus  anticus  major. 

The  hypaxial  muscle  of  the  lumbar  region  and  pedicle  is  an  enormous  mass  occupying 
the  region  between  the  transverse  processes  and  the  bodies  of  the  vertebrae  and  extending  from 
the  last  caudal  vertebra  to  the  eleventh  rib.  Dorsad  it  is  in  relation  in  its  whole  length  with 
the  transversarius.  Mesad  it  is  in  contact  with  its  fellow,  the  chevron  bones  being  interposed 
as  far  rostrad  as  the  anus,  beyond  which  the  muscle  twists  somewhat  on  itself,  so  that  its  mesal 
surface  becomes  meso-ventral.  Against  this  surface  rest  the  kidneys  and  ureters,  and  between 
the  muscles  of  the  two  sides  are  interposed  the  aorta  and  postcavse.  Superficially  in  the  abdomi- 
nal region  the  muscle  is  covered  by  the  transversalis,  the  obliqui  and  lumbar  aponeurosis;  in 
the  pedicle  it  is  partially  overlain  and  concealed  by  the  ischio-caudalis  and  the  aponeurosis  of 
the  rectus.  The  lumbar  and  caudal  nerves  and  blood  vessels  pass  dorsal  to  it  to  the  cleft  between 
it  and  the  transversarius. 

In  structure  it  resembles  the  longissimus  dorsi,  being  divided  caudally  into  two  tracts  which 
become  merged  rostrad.  Its  lateral  tract  begins  as  a  great  tendon  attached  to  the  ventral 
aspect  of  the  caudal  vertebrae,  and  receiving  minor  tendons  laterad  from  the  region  of  the  rudi- 
mentary transverse  processes.  From  the  beginning  of  the  flukes  rostrad  to  the  level  of  the  hypo- 
gastric  arteries,  this  great  tendon  resolves  itself  into  a  series  of  five  smaller  tendons  of  origin, 
which  add  themselves  to  the  mesal  tract  of  the  muscle.  This  tract  begins  at  the  junction  of  the 
flukes  and  pedicle  by  fleshy  fasciculi  derived  from  the  deep  surface  of  the  great  tendon.  Rostrad 
it  increases  in  size,  deriving  additional  fasciculi  from  two  sources,  mesad  from  the  chevron  bones 
and  laterad  from  the  tendon  slips  before  mentioned.  In  the  abdominal  region  it  gains  attach- 
ments to  the  bodies  of  the  vertebrae  and  the  ventral  surfaces  of  the  transverse  processes,  extending 


SCHULTE,  SEI  WHALE.  427 

farther  laterad  upon  the  latter  as  it  proceeds  rostrad,  and  making  fibrous  arches  over  the  lumbar 
vessels,  beside  the  vertebral  bodies.  The  lateral  tract  is  situated  between  the  foregoing  and  the 
transversarius.  At  the  beginning  of  the  pedicle  it  arises  from  the  sides  of  the  vertebrae,  receiving 
also  a  tendon  of  origin  from  the  great  tendon  of  the  mesal  tract.  It  enlarges  rostrad  deriving 
fleshy  fasciculi  from  the  sides  of  the  vertebrse,  and  in  addition  receives  seven  tendons  of  origin 
from  the  interval  between  it  and  the  transversarius.  These  arise  from  the  bodies  of  the  ver- 
tebrae and  are  at  first  incorporated  in  the  intermuscular  septum,  their  line  of  origin  extending 
rostrad  about  half  the  length  of  the  pedicle.  They  are  directed  mesad  as  well  as  rostrad  passing 
superficial  to  the  fleshy  belly  of  the  lateral  tract  until  they  come  to  lie  beside  the  great  tendon 
of  the  mesal  tract.  They  end  in  fleshy  bundles  which  are  added  to  the  mesal  aspect  of  the 
lateral  tract.  As  it  is  followed  rostrad  this  portion  of  the  muscle  comes  more  and  more  to  overlie 
the  mesal  tract,  with  which  in  the  lower  abdomen  it  becomes  inextricably  blended.  The  fas- 
ciculi of  both  tracts,  while  in  general  longitudinal,  have  an  inclination  laterad,  passing  from 
mesal  origin  to  lateral  insertion,  exception  made  of  the  vertebral  insertions  already  mentioned, 
which  belong  to  the  mesal  tract.  In  the  pedicle  the  whole  muscle  including  its  tendons  is  cov- 
ered by  a  dense  aponeurosis  which  is  attached  mesad  to  the  extremities  of  the  chevron  bones, 
and  laterad  to  the  septum  between  it  and  the  transversarius.  From  the  first  chevron  rostrad 
this  becomes  replaced  by  a  muscular  layer  which  ensheaths  the  longitudinal  tracts  and  their 
tendons,  its  own  fasciculi  having  a  more  oblique  direction.  On  its  deep  surface  it  is  closely  joined 
to  the  rest  of  the  muscle  by  exchange  of  fasciculi. 

The  insertion  is  into  the  bodies  of  the  abdominal  vertebrae  as  far  rostrad  as  the  first  lumbar, 
into  the  ventral  surfaces  of  their  transverse  processes  to  a  degree  which  increases  rostrad,  into 
the  caudal  border  and  ental  surface  of  the  last  rib  in  its  whole  length,  and  into  the  ental  surfaces 
.of  the  twelfth  and  eleventh  ribs  in  the  region  of  their  angles.  It  is  innervated  by  branches  of 
the  lumbar  nerves  as  they  pass  obliquely  through  its  substance. 

Dorsal  musculature. —  In  the  description  of  these  muscles  I  have  used  the  terminology  and 
classification  of  the  human  anatomists,  following  Eisler  1  as  closely  as  the  nature  of  the  case 
permitted.  I  have  made  but  few  references  to  the  literature  of  cetacean  myology,  because 
this  is  almost  confined  to  the  Odontoceti  and  has  been  summarized  by  Leche,2  while  Carte  and 
MacAlister's  account  of  Balcenoptera  is  too  abbreviated  and  incomplete  to  be  of  much  assistance. 
I  have  therefore  limited  myself  to  memoranda  of  the  conditions  observed,  and  here  have  sought 
to  describe  the  general  relations  and  extent  of  the  several  systems  rather  than  to  enter  upon  their 
structure  in  detail,  for  which  the  small  size  of  this  foetus  makes  it  rather  unfavorable  material. 

Spino-costal  muscles. —  This  layer  is  very  rudimentary  as  it  is  for  the  most  part  repre- 
sented by  a  fascial  layer.  The  serratus  posticus  inferior  is  very  thin  and  its  fasciculi  insert  upon 
the  6th,  7th  and  8th  ribs  near  their  angles.  It  is  covered  by  the  latissimus  dorsi.  I  failed  to 
find  a  serratus  posticus  superior.  Neither  are  mentioned  by  Carte  and  MacAlister. 

Spino-dorsal  muscles. —  These  muscles  are  of  enormous  size  and  for  the  most  part  so  inti- 
mately connected  by  exchange  of  bundles,  that  their  resolution  into  tracts  is  more  than  usually 
difficult  and  at  best  schematic.  An  exception  is  present  in  the  transversarius,  which  in  its  whole 
length  is  separated  from  the  other  spinodorsal  muscles  by  a  definite  septum.  From  this  mesad 

1  Eisler,  P.     Die  Muskeln  des  Stammes,  in  Bardeleben's  Hanb.  der  Anat.  des  Mensch.  Jena,  1912.     See  also  Henle,  Anat.  des 
Menschen.     Braunschweig,  1873. 

-  Braun's  Thierrcich,  Siiugethiere. 


428  SCHULTE,  SEI  WHALE. 

to  the  spines  by  far  the  greatest  area  is  occupied  by  the  longissimus,  which  increases  in  bulk  as 
far  rostrad  as  the  thorax,  there  diminishing  so  that  only  a  ribbon-like  band,  narrow  and  deep, 
is  continued  to  the  head.  Between  this  and  the  transversarius,  beginning  in  the  upper  thorax, 
is  interposed  the  triangular  trachelo-mastoid,  which  is  well  demarcated  from  the  longissimus  by 
a  strong  septum,  while  less  firm  and  but  scanty  connective  tissue  intervenes  between  it  and 
the  transversarius.  It  seems  to  receive  no  fasciculi  from  that  muscle.  The  longissimus  abuts 
upon  the  spines  in  the  pedicle,  yet  even  here  fasciculi  of  the  transverso-spinalis  tract  separate 
it  deeply  from  their  bases.  These  elements  increasing  in  size  rostrad  come  to  occupy  more  and 
more  of  the  sides  of  the  spines  and  in  the  upper  lumbar  region  form  a  narrow  tract  intervening 
between  the  longissimus  and  the  spines.  In  this  region  the  separation  of  the  two  muscles  is 
very  imperfect.  From  the  last  dorsal  vertebra  the  superficial  stratum  of  the  transverso-spinalis, 
the  semispinalis,  increases  enormously  in  size  and  forces  the  diminishing  longissimus  laterad, 
its  very  massive  belly  (semispinalis  capitis)  is  the  largest  muscle  of  the  neck  and  gains  a  broad 
and  deep  insertion  upon  the  occipital.  Superficial  and  partly  concealing  this  muscle  in  the 
neck  is  the  splenius  capitis,  which  inserts  in  intimate  association  with  the  trachelo-mastoid  into 
the  mastoid  region.  With  this  by  way  of  introduction  we  may  turn  to  a  brief  consideration  of 
the  individual  muscles. 

The  splenius  arises  from  the  aponeurosis  covering  the  longissimus  by  means  of  which  it 
is  attached  to  the  spines  in  the  dorsal  region.  Its  fasciculi  are  directed  rostrad  and  laterad, 
and  condensing  towards  its  insertion  and  blending  to  some  extent  with  the  trachelomastoid,  it 
inserts  into  the  caudal  extremity  of  the  squamosal  close  to  its  junction  with  the  mastoid  and 
into  a  strong  tendon,  which  passes  rostrad  from  this  region  to  the  postorbital  process  of  the  frontal 
and  the  base  of  the  zygoma.  In  its  course  this  tendon  is  adherent  to  the  underlying  periosteum. 
It  gives  insertion  caudad  in  addition  to  the  splenius  and  trachelomastoid,  to  some  of  the  fasci- 
culi of  the  sternomastoid  and  mastohumeral.  In  front  it  gives  origin  in  part  to  the  deep  portion 
of  the  masseter. 

The  trachelomastoid  is  of  moderate  size  and  triangular  in  shape.  It  arises  from  the  ectal 
surfaces  of  the  first  four  ribs,  mesal  to  the  transversarius  slips,  and  from  the  transverse  processes 
of  the  lower  cervical  vertebrae.  It  is  inserted,  fused  with  the  splenius,  into  the  caudal  portion  of 
the  squamosal  and  into  the  tendon  just  described. 

The  longissimus  dorsi  occupies  the  region  between  the  transverse  and  the  spinous  processes 
as  far  as  the  thorax,  where  it  is  displaced  laterad,  yielding  an  increasing  area  immediately  adja- 
cent to  the  spines  to  the  transversospinalis  (semispinalis  capitis).  Here  the  muscle  rapidly 
diminishes  in  size  and  only  a  rather  slender  belly  gains  attachment  to  the  exoccipital.  In  the 
pedicle  a  ventro-lateral  portion,  the  iliocostalis  (sacrolumbalis  of  Stannius)  is  distinguishable, 
separated  from  the  dorso-median  portion  by  a  fibrous  septum,  which  is  nevertheless  pierced  for 
the  passage  of  tendons  which  give  origin  to  fasciculi  of  the  iliocostalis.  Rapp  considered  that 
the  two  portions  were  so  intimately  united  as  to  constitute  a  single  muscle.  Stannius  found  them 
separated  throughout  by  a  septum  and  assigns  all  the  fasciculi  that  insert  into  transverse  pro- 
cesses and  ribs  to  his  sacrolumbalis.  The  longissimus  begins  by  a  stout  tendon  arising  from  the 
dorsum  of  the  last  vertebra.  It  passes  rostrad  receiving  slips  from  the  spinous  processes, 
muscular  fasciculi  first  appearing  near  the  extremity  of  the  pedicle.  Throughout  the  caudal 
and  lumbar  region  it  is  recruited  by  slips  from  the  spinous  and  accessory  processes,  and  con- 
tinues to  receive  slips  from  the  latter  source  in  the  thorax,  where  it  has  abandoned  its  posi- 
tion beside  the  spines.  In  addition  it  receives  augmentation  of  fasciculi  from  the  strong 


SCHULTE,  SE1  WHALE.  42!) 

aponeurosis,  which  covers  its  surface.  This  is  especially  conspicuous  in  the  thorax  and 
neck,  where  a  considerable  portion  of  the  muscle  along  its  ventro-lateral  margin  is  derived 
from  this  source.  The  iliocostalis  begins  as  a  series  of  tendons  derived  from  the  ventrolateral 
margin  of  the  longissimus.  The  first  of  these  leaves  the  tendon  of  origin  of  the  latter  at  the 
junction  of  the  pedicle  with  the  flukes.  Ten  such  tendons  in  all  were  present,  increasing  in  size 
to  the  middle  of  the  pedicle  and  then  diminishing.  The  fourth,  fifth  and  sixth  are  the  largest. 
These  all  pierce  the  septum  which  separates  the  longissimus  and  iliocostalis.  In  addition  the 
muscle  receives  slips  from  the  accessory  processes.  The  fasciculi  are  directed  nearly  longitudi- 
nally, but  with  a  slight  deviation  laterad  and  ventrad,  to  their  insertions  by  mixed  tendinous 
and  fleshy  fibres  into  the  transverse  processes  of  the  lumbar,  thoracic  and  cervical  vertebrae 
(iliocostalis) ,  and  into  a  vertical  line  upon  the  exoccipital  between  the  trachelo-occipital  muscle 
mesad  and  the  obliquus  superior  laterad  (longissimus).  In  the  thoracic  region  slips  are  also 
attached  to  the  ribs  mesal  to  their  angles  and  to  the  insertions  of  the  trans versarius. 

The  transverso-spinalis  consists  of  fasciculi  extending  from  the  transverse  processes  to  the 
spines  of  the  vertebra;  with  a  general  direction  rostro-mesad.  It  may  be  resolved  into  a  super- 
ficial portion  (semispinalis)  and  a  deep  portion,  multifidus,  though  many  fasciculi  extend  from 
one  to  the  other.  In  the  pedicle  where  the  whole  system  is  of  small  size  and  for  the  most  part 
under  cover  of  the  longissimus,  from  which  it  is  but  imperfectly  separate,  I  was  obliged  to  give 
over  the  attempt  to  analyze  its  components.  As  the  thorax  is  approached  the  semispinalis 
increases  in  size  and  attains  considerable  depth,  gradually  making  its  appearance  between  the 
spines  and  the  longissimus.  Its  fasciculi  arising  from  accessory  processes  are  inserted  into 
the  spines  of  more  rostral  vertebrae.  The  fasciculi  have  a  very  oblique  course  and  pass  over 
several  vertebrae  from  origin  to  insertion.  From  about  the  mid-dorsal  region  the  insertion  into 
spines  ceases,  indeed  a  few  fasciculi  now  arise  from  this  source,  and  the  origin  from  the  accessory 
processes  enlarges  spreading  on  to  the  bases  of  the  transverse  processes.  The  muscle  becomes 
very  bulky  rising  high  above  the  level  of  the  spines  as  it  approaches  its  insertion  into  a  large 
area  on  the  supraoccipital,  between  the  midline  and  the  attachment  of  the  longissimus.  This 
portion  is  the  semispinalis  capitis  and  constitutes  by  far  the  major  part  of  the  whole  system. 
From  its  deep  surface,  in  the  upper  thoracic  and  cervical  region,  several  large  bundles  are  given 
to  the  underlying  multifidus.  The  semispinalis  cervicis,  rectus  capitis  posticus,  obliquus  and 
multifidus  are  exposed  on  its  reflection. 

The  semispinalis  cervicis  is  a  small  muscle  arising  from  the  transverse  processes  of  the  lower 
cervical  and  the  first  three  thoracic  vertebrae.  It  is  directed  obliquely  rostro-mesad  and  inserts 
upon  the  arches  of  the  epistropheus  and  atlas,  many  of  its  fasciculi  passing  uninterruptedly  into 
the  rectus  capitis  posticus. 

The  multifidus  is  composed  of  bundles  passing  between  spines  and  transverse  processes. 
In  the  upper  lumbar  region  they  have  a  moderate  obliquity  passing  over  three  or  four  vertebrae 
in  their  course  from  origin  to  insertion.  In  the  thorax  their  course  becomes  more  longitudinal 
and  some  of  the  superficial  bundles  are  of  reversed  obliquity  passing  from  thoracic  spines  to 
cervical  transverse  processes.  As  a  whole  this  system  is  of  small  size  filling  the  interval  between 
accessory  and  spinous  processes.  Caudad  it  resisted  my  efforts  to  separate  it  from  the  semi- 
spinalis, rostrad  while  more  independent  it  yet  receives  several  slips  from  the  deep  surface  of 
that  muscle.  I  did  not  examine  the  submultifidus.  Interspinales  are  present,  paired  and  of 
moderate  development. 

The  rectus  capitis  posticus  I  could  not  resolve  into  major  and  minor.     It  arises  broadly  from 


430  SCHULTE,  SEI  WHALE. 

the  arches  of  the  atlas  and  epistropheus  and  the  intervening  ligament,  receiving  a  broad  super- 
ficial fasciculus  from  the  semispinalis  capitis  and  having  some  of  its  bundles  below  this  con- 
tinuous with  that  smaller  member  of  the  transversospinal  system,  which  I  have  taken  for  the 
semispinalis  cervicis.  The  muscle  has  considerable  thickness  and  inserts  into  the  occipital 
between  the  margin  of  the  foramen  magnum  and  the  attachment  of  the  semispinalis  capitis. 
Stannius '  in  Phocccna  found  this  muscle  incorporated  into  the  semispinalis.  Murie "  finds 
two  recti  in  Globiocephalus  closely  woven  together. 

The  rectus  capitis  lateralis  is  a  short  thick  muscle  arising  from  the  transverse  process  of 
the  atlas  and  the  adjacent  border  of  the  articular  process,  and  inserting  upon  the  paroccipital 
process,  its  fasciculi  having  a  slightly  oblique  direction  and  spreading  out  at  their  occipital 
attachment. 

The  obliquus  capitis  superior  arises  from  the  transverse  process  and  dorsal  arch  of  the  atlas, 
and  ascends  to  a  rather  large  insertion  upon  a  ridge  at  the  extremity  of  the  exoccipital  dorsal 
to  the  insertion  of  the  rectus  capitis  lateralis,  and  lateral  to  the  next  following  muscle. 

This  is  a  sagittal  trachelo-occipital  muscle,  the  origin  of  which  extends  from  the  accessory 
process  of  the  first  thoracic  vertebra  to  the  dorsal  arch  of  the  atlas,  arising  from  the  arches  of 
the  cervical  vertebrae  in  a  position  corresponding  to  the  prolongation  of  the  line  of  the  accessory 
processes.  Increasing  greatly  in  size  in  the  upper  cervical  region  it  is  inserted  into  the  occipital 
bone  between  the  rectus  capitis  posticus  and  the  longissimus  and  seems  to  be  a  derivative  of 
the  semispinalis  capitis.  It  is  placed  dorsomesal  to  the  dorsal  divisions  of  the  cervicle  nerves. 
This  muscle  is  described  and  figured  in  Globiocephalu's  by  Murie  3  who  interprets  it  as  trachelo- 
mastoid.  He  also  describes,  in  addition  to  the  rectus  capitis  lateralis,  two  atlanto-occipital 
muscles,  which  he  designates  superior  and  inferior  oblique. 

The  transversarius  occupies  the  region  of  the  transverse  processes  extending  from  the  last 
caudal  vertebra  to  the  atlas.  It  is  separated  from  the  longissimus  by  a  strong  septum  and  is 
itself  enclosed  in  a  sheath,  of  great  strength  in  the  pedicle  and  abdominal  portion  of  its  course, 
but  becoming  tenuous  in  the  thorax.  In  the  pedicle  the  muscle  is  present  in  two  divisions,  one 
dorsal  to  the  transverse  processes,  one  ventral,  this  latter  being  the  transversarius  inferior  of 
Stannius.  The  muscle  broadens  in  surface  view  to  the  middle  of  the  pedicle,  then  gradually 
contracts  becoming  a  narrow  band  opposite  the  vulva,  where  the  inferior  division  is  greatly 
reduced  and  merges  with  the  body  of  the  muscle.  From  this  point  it  is  continued  narrow  but 
of  very  considerable  transverse  depth  to  the  last  rib.  In  its  costal  portion  the  muscle  is  thinner 
but  somewhat  broader  giving  slips  from  its  ventral  margin  to  each  of  the  ribs  near  their  angles 
as  far  as  the  first,  where  it  enters  the  interval  between  the  scalene  mass  and  the  trachelo-mastoid, 
and  is  continued  as  a  slender  fasciculus  to  the  transverse  process  of  the  axis,  being  placed  immedi- 
ately dorsal  to  the  origin  of  the  levator  scapulae.  In  this  portion  of  its  course  it  is  distinct  from 
the  intertransversarii  dorsales  and  separated  from  them  by  the  cervical  insertions  of  the  longis- 
simus, having  much  the  position  and  arrangement  of  the  human  intertransversarius  lateralis 
longus.  The  thoracic  portion  is  considerably  narrower  than  in  Phoccena  where  Stannius  found 
it  expanding  ventrad  as  a  thin  sheet  as  far  as  the  origin  of  the  obliquus  externus.  Rapp 


1  Stannius,  op.  tit.,  p.  29. 

2  Murie,  op.  cit.,  p.  282. 

"'  Murie,  op.  cit.,  \>.  282  and  li^s.  C>7,  OS. 


SCHULTE,  SEI  WHALK.  431 

described  it  as  an  independent  muscle  —  m.  costalis,  but  Stannius  concurs  with  Meckel  in 
assigning  it  to  the  system  of  the  transversarius,  which  it  continues  forward  upon  the  thorax. 
The  transversarius  arises  by  a  series  of  slips  from  the  side  of  the  last  vertebra  and  from  the 
transverse  processes  of  the  caudal,  lumbar  and  thoracic  vertebrae.  It  is  inserted  similarly  by 
slips  into  the  transverse  processes  of  more  rostral  vertebrae  and  in  the  thoracic  region  into  the 
ribs.  The  inferior  division  in  the  pedicle  has  an  analogous  arrangement  ventral  to  the  trans- 
verse processes,  arising  from  the  side  of  the  last  vertebras  and  from  transverse  processes,  insert- 
ing into  more  rostral  transverse  processes.  It  becomes  much  reduced  near  the  level  of  the 
vulva  and  its  remnant  there  merges  with  the  portion  situated  dorsal  to  the  transverse  processes. 


THE  UPPER  ALIMENTARY  TRACT. 
(Plate  LXIX,  Fig.  1.) 

Cavurn  oris  proprium. —  In  the  absence  of  prominent  alveolar  processes,  though  in  the 
case  of  the  maxillae  this  requires  some  qualification,  the  dento-labial  sulci  may  serve  as  the 
boundary  between  the  vestibule  and  the  mouth  cavity  proper.  The  course  of  the  sulci  has 
already  been  described.  On  dissection  the  inferior  furrow  was  found  to  send  ventrad  into  the 
alveolar  gutter  of  the  mandible  a  low  keel,  to  which  the  dental  anlages  were  attached  or  at  least 
immediately  adjacent.  These  were  in  general  subhemispherical,  about  1  mm.  in  diameter, 
although  a  few  were  slightly  elongate  sagittally.  In  the  midregion  they  were  separated  by 
intervals  about  equal  to  the  anlages  in  length,  but  towards  the  symphysis  they  were  more  closely 
set.  The  caudal  third  of  the  series  was  damaged  by  a  crushing  of  the  brittle  jaw  which  occurred 
during  dissection,  so  that  their  shape  could  not  be  satisfactorily  determined.  The  total  number 
was  about  thirty.  The  superior  dento-labial  sulcus  was  deepened  along  the  margin  of  the 
maxilla,  but  had  no  dental  anlages  attached  to  it.  These  were  contained  in  the  cavity  of  the 
maxilla,  which  in  its  caudal  two  thirds  presented  a  corresponding  convexity  on  its  palatine 
aspect,  which  would  seem  therefore  equivalent  to  a  alveolar  process. 

The  floor  of  the  oral  cavity  comprises  the  alveolingual  region  and  the  tongue.  The  alveo- 
lingual  region  is  very  extensive  and  is  the  expression  of  the  disparity  in  size  between  the  tongue 
and  the  wide  arch  of  the  mandibles.  Its  floor  is  wrinkled  and  furrowed,  but  upon  depressing 
the  tongue  and  so  stretching  the  mandibular  pouch,  these  surface  markings  are  effaced  and 
appear  therefore  to  be  but  the  accompaniments  of  the  distensibility  of  the  region. 

The  tongue  is  broad  and  squat,  rising  but  moderately  above  the  alveolingual  region.  It 
has  a  length  of  48  mm.  and  its  greatest  breadth  is  24  mm.  Its  tip  is  free  for  a  sagittal  distance 
of  11  mm.  In  spite  of  its  great  size  the  tongue  comes  far  short  of  filling  the  enormous  mouth, 
and  there  is  at  its  sides  a  space  of  1  or  2  mm.  between  it  and  the  mandibles,  while  its  tip  fails 
of  reaching  the  symphysis  by  7  mm.  Similarly  between  the  base  of  the  tongue  and  the  faucial 
orifice  there  is  an  interval  of  6  mm.  Here  the  floor  of  the  mouth  is  depressed  to  a  shallow  fossa, 
the  mucosa  of  which  is  marked  by  fine  grooves  and  ridges.  This  depression  is  situated  entirely 
rostrad  of  the  hyoid.  Its  floor  forms  a  prominence  between  the  hyoglossi  and  is  reinforced  by 
a  local  increase  of  the  transverse  lingualis.  Its  presence  appears  to  be  associated  with  the 
feeble  development  of  the  radix  linguae.  These  facts  and  especially  its  position  seem  to  pre- 
clude all  attempt  to  bring  it  into  any  direct  relation  with  the  pharyngeal  pouch  of  the  elephant 


432  SCHULTE,  SEI  WHALE. 

described  by  Watson.1  There  is  no  foramen  ccecum  and  no  circumvallate  papillae  are  present. 
The  tip  of  the  tongue  is  rounded,  and  has  a  thin  crenate  border  covered  by  slightly  roughened 
epithelium.  On  the  dorsum,  from  each  end  of  this  border  a  low  ridge,  rather  rough  and  papil- 
la ted  is  prolonged  for  about  half  the  length  of  the  organ.  Elsewhere  the  surface  is  very  smooth. 
The  midline  is  marked  by  a  depression  which  broadens  at  the  tip,  and  only  partially  corresponds 
to  the  vomerine  ridge  on  the  palate.  The  sublingua  is  represented  by  a  triangular  area  on 
the  ventral  surface  of  the  free  extremity.  It  is  defined  by  two  furrows  which  converge  towards 
the  free  margin  which  they  fail  of  reaching  by  about  2  mm.  Their  terminal  segments  do  not 
meet  but  become  parallel.  They  thus  define  a  triangle  the  apex  of  which  is  produced  into  a 
narrow  strip.  This  latter  is  slightly  depressed,  while  the  triangle  is  convex  and  rises  a  little  above 
the  adjacent  surface.  There  is  no  frenulum,  and  no  plica  fimbriata.  The  tongue  is  very  soft, 
which  depends  in  part  upon  the  arrangement  of  the  genioglossi  and  the  interposition  between 
them  of  a  considerable  quantity  of  fat. 

The  roof  of  the  mouth  is  narrower  and  more  pointed  rostrally  than  the  floor,  depending 
upon  the  less  development  of  the  upper  lips  and  their  being  overlapped  in  a  considerable  portion 
of  their  course  by  the  prominent  margins  of  the  lower.  The  palate  in  the  region  of  the  rostrum 
is  triangular  attaining  its  greatest  breadth  in  front  of  the  temporal  muscles.  It  then  narrows 
rapidly,  a  shallow  depression  being  formed  on  each  side,  between  the  margin  of  the  palate  process 
of  the  maxilla  rostrad,  the  temporal  muscle  laterad,  and  the  internal  pterygoid  mesad.  This 
is  separated  from  the  orbital  aponeurosis  by  a  small  quantity  of  fat;  its  epithelium  is  pigmented. 
Caudal  of  this  the  oral  cavity  is  truncated  by  the  transverse  partition  of  the  velum.  The  median 
line  of  the  palate  is  marked  by  a  sagittal  ridge  in  its  middle  third,  which  corresponds  to  the 
ventral  border  of  the  vomer.  This  is  bounded  by  two  narrow  concavities  which  run  together 
in  front  of  the  ridge  and  continue  almost  to  the  tip  of  the  rostrum.  Lateral  to  these  and  extend- 
ing to  the  labial  sulci  are  two  broader  convexities  —  the  displaced  alveolar  processes.  In  no 
portion  of  the  oral  cavity  proper,  nor  in  the  vestibule  could  I  find  evidence  of  the  presence  of 
salivary  glands. 

Fauces. —  The  fauces  are  drawn  out  to  a  narrow  canal,  measuring  in  length  13.5  mm.  from 
the  oral  orifice  to  the  edge  of  the  velum  palati  in  the  pharynx.  Transversely  the  lumen  is  4  mm., 
vertically  it  increases  from  a  mere  slit  proximad  to  about  4  mm.  distad  as  it  joins  the  pharynx. 
Its  oral  orifice  is  about  midway  between  the  roof  and  floor  of  the  mouth,  the  latter  deepening 
to  a  shallow  fossa  between  it  and  the  tongue.  The  diaphragm-like  plate  that  terminates  the 
oral  cavity  caudad  is  formed  by  the  palatoglossus  muscle,  a  tubular  extension  of  which  is  pro- 
longed upon  the  faucial  canal.  This  passage  after  a  horizontal  course  caudad  for  about  half  its 
length,  turns  abruptly  ventrad  to  reach  the  dorsum  of  the  hyoid  and  again  approaching  the 
horizontal  enters  the  most  ventral  portion  of  the  pharynx  to  the  right  of  the  epiglottis.  Its 
wall  appears  faintly  granular  under  a  lense,  which  is  probably  due  to  the  presence  of  glands. 
I  found  no  trace  of  a  tonsil. 

Pharynx. —  As  compared  with  the  narrow  fauces  and  oesophagus,  the  pharynx  forms  a  marked 
dilatation  of  the  alimentary  canal,  in  the  transverse  as  well  as  in  its  dorso-ventral  diameter. 
It  attains  its  greatest  breadth  between  the  hyoid  bars;  rostrad  it  is  contracted  between  the 
auditory  bullse,  here  resting  against  the  basis  cranii  and  forming  a  funnel-shaped  approach  to 


1  Watson,  M.     Contributions  to  the  anatomy  of  the  Indian  Elephant  (Elephas  indicus).     P.  XIII,  The  Head.     Jour.  Anat.  and 
Pliys.,  Vol.  8,  1873,  p.  85.     Vide  Weber,  Die  Saugetiere,  1904,  p.  722. 


SCHULTE,  SEI  WHALE.  433 

the  choanse.  Caudad  it  diminishes  more  gradually  as  far  as  the  thyroid  cartilage,  but  opposite 
to  it  it  abruptly  narrows  to  join  the  oesophagus.  The  maintenance  of  its  transverse  diameter 
in  the  region  of  the  laryngeal  junction  stands  in  relation  to  the  great  breadth  of  the  trachea. 
The  interior  of  the  pharynx  is  profoundly  modified  as  a  consequence  of  the  retrovelar  position 
of  the  epiglottis  and  the  concomitant  lengthening  of  the  fauces  to  a  tubular  passage,  the  bucco- 
pharyngeal  canal  of  Turner.  This  latter  depends  for  its  formation  upon  a  lengthening  of  the 
velum  palati,  which  projects  far  caudad  into  the  cavity  of  the  pharynx  terminating  as  a  crescentic 
fold,  the  horns  of  which  prolonged  upon  the  sides  of  the  pharynx  are  the  arcus  palatopharyngei. 
In  the  Odontoceti  these  are  prolonged  upon  the  dorsal  wall  of  the  pharynx  forming  a  muscular 
annulus  palato-pharyngeus  (Ruckert).  In  this  fetus  the  annulus  is  not  circular,  but  rather 
pyriform  with  the  wide  end  rostrad.  Caudad  the  narrow  part  of  the  annulus  is  formed  by  a 
thick  muscular  ridge  of  the  dorsal  wall,  prolonged  upon  the  sides  by  fairly  well  defined  ridges, 
which  can  be  followed  to  the  back  of  the  hyoid  beside  the  epiglottis.  They  owe  their  promi- 
nence chiefly  to  deep  sulci  at  their  caudo-ventral  margins,  which  separate  them  from  the  larynx 
which  between  them  rises  into  the  pharynx.  The  position  of  this  ridge  would  suggest  that  its 
muscular  basis  is  a  specialization  of  the  middle  constrictor,  rather  than  an  extension  of  the 
palatopharyngeus.  The  annulus  in  this  foetus  is  therefore  composed  of  two  crescentic  ridges, 
with  their  cornua  approximated  but  not  actually  continuous,  nor  even  in  line  with  one  another. 
The  dorso-caudal  crescent  embraces  the  arytenoids,  the  ventro-rostral  corresponds  to  the  epi- 
glottis but  abutts  closely  upon  it  only  in  front  and  on  the  left  side.  A  low  oblique  ridge  extends 
from  the  velum  to  join  the  horn  of  the  dorso-caudal  crescent  opposite  the  interval  between 
arytenoid  and  epiglottis.  Their  junction  is  marked  by  a  small  triangular  elevation.  This  ridge 
defines  the  region  of  the  faucial  orifice,  in  which  is  also  contained  the  base  of  the  epiglottis.  The 
position  of  the  larynx  is  already  asymmetrical  and  a  rod  passed  into  the  fauces  here  emerges 
to  the  right  of  the  epiglottis.  Dorsal  and  caudal  to  the  oblique  ridge  the  lateral  wall  is  concave 
and  on  the  left  side  shows  the  impression  of  the  arytenoid  cartilage.  This  concavity  is  limited 
in  front  by  a  ridge  which  broadens  ventrad,  there  forming  a  broad  elevation  upon  which  termi- 
nates the  short  arcus  palatopharyngeus.  Carte  and  MacAlister  have  noted  the  absence  of  the 
uvula  in  B.  rostrata  (  =  acuto-rostrata) ,  an  observation  confirmed  by  Turner,  and  also  true  of  this 
foetus.  The  former  authors. describe  a  "peculiar,  preepiglottic  hoodlike  fold"  which  they  found 
capable  of  being  drawn  over  the  epiglottis  and  inferred  that  it  covered  and  protected  the  larynx 
during  deglution.  Turner  states  explicitly  that  no  such  fold  was  present  in  his  specimen,  but 
a  comparison  of  the  figures  1  leaves  no  room  to  doubt  that  both  he  and  they  had  before  them 
the  same  structure,  which  Turner  correctly  designated  velum.  That  he  failed  to  recognize  in 
it  the  peculiar  hood-like  fold  of  Carte  and  MacAlister  was  in  part  due  to  their  conjecture  as  to 
its  function,  but  especially  to  their  location  of  the  faucial  orifice  dorsal  and  not  ventral  to  their 
fold.  In  this,  I  believe,  they  were  grossly  mistaken,  and  that  the  probe  in  their  illustrations  does 
not  follow  the  faucial  passage  but  is  thrust  through  the  velum  itself.  A  consideration  of  the 
position  of  the  velum  between  the  faucial  canal  and  the  pharynx  reveals  the  possibility  of  such 
an  error,  especially  if  they  were  dealing  with  material  advanced  in  decomposition  —  fourteen 
days  elapsed  between  the  capture  of  the  whale  and  the  beginning  of  their  dissection. 

As  has  been  said,  the  faucial  passage  is  not  straight,  but  curves  sharply  ventrad  in  its  caudal 


1  Carte  and  MacAlister,  op.  cit.,  pi.  vi,  figs.  5-9. 
Turner,  op.  cil.,  pi.  viii,  fig.  31. 


434  SCHULTE,  SET  WHALE. 

portion  to  reach  the  dorsum  of  the  hyoid.  In  consequence  the  faucial  surface  of  the  velum  does 
not  form  a  simple  plane,  but  conforms  to  the  direction  of  the  canal.  It  is  at  first  nearly  hori- 
zontal, it  then  slopes  caudad  and  ventrad,  and  finally  becomes  horizontal  again  and,  forming  the 
crescentic  fold  described  above,  projects  into  the  pharynx  as  a  horizontal  shelf.  Its  dorsal 
surface  has  a  corresponding  relief,  with  this  difference,  that  at  the  junction  of  the  first  hori- 
zontal plane  with  the  sloping  portion  a  prominent  transverse  ridge  is  formed.  This  ridge  cor- 
responds to  the  caudal  border  of  the  tensor  palati,  though  it  is  rendered  more  prominent  by  a 
diminution  in  the  thickness  of  the  mucosa  behind  it.  From  the  ridge  rostrad  the  velum  forms 
a  continuation  of  the  floor  of  the  nasal  fossa  continuing  the  plane  of  the  palate.  Caudal  to  the 
ridge  the  dorsum  of  the  velum  is  deeply  concave,  forming  a  shallow  bay  or  sinus,  which  extends 
distad  to  the  shelf-like  margin  of  the  velum.  Laterad  the  sinus  involves  the  wall  of  the  pharynx 
and  attains  considerable  depth  above  the  arcus  palato-pharyngeus.  In  Carte  and  MacAlister's 
plate  vi,  fig.  6,  the  sjnus  and  its  limiting  folds  is  tolerably  well  shown,  and  the  probe,  I  believe, 
passes  through  its  fundus  to  enter  the  mouth. 

In  the  muscular  wall  of  the  pharynx  Turner1  found  "at  least  two  pairs  of  constrictors" 
arising  from  the  hyoid  and  thyroid,  nor  could  I  find  evidence  of  the  presence  of  the  superior, 
the  internal  pterygoid  serving  only  to  attach  the  very  strong  fibrous  tissue  of  the  pharynx,  but 
giving  it  apparently  no  muscular  fasciculi,  nor  could  I  find  any  of  lingual  origin.  The  inferior 
constrictor  arises  from  the  whole  lateral  or  dorsal  margin  of  the  thyroid  cartilage  including  its 
posterior  cornu,  and  is  inserted  into  the  dorsal  raphe  of  the  pharynx.  The  rostral  fasciculi  were 
transverse  and  not  clearly  to  be  distinguished  from  those  of  the  middle  constrictor,  so  that  the 
two  muscles  appeared  to  blend  rather  than  overlie  one  another.  This  blending  was  due  to  a 
fibrous  arch  passing  from  the  middle  to  the  inferior  constrictor,  dorsal  to  the  entrance  between 
them  of  the  glossopharyngeal  nerve  and  stylopharyngeus  muscle,  and  the  fasciculi  arising  from 
this  arch  effectually  closed  the  gap  between  the  constrictors.  The  most  caudal  fasciculi  from 
the  posterior  cornu  have  a  very  oblique  course,  ascending  to  their  insertion.  In  their  course 
they  are  nearly  independent  of  the  rest  of  the  muscle  and  overlie  the  fasciculi  from  the  base 
of  the  cornu.  These  fasciculi  from  the  two  sides  make  a  V  open  caudad,  at  the  apex  of  which 
the  oesophagus  emerges.  As  the  origin  of  this  muscle  is  much  larger  than  its  insertion,  it  is 
necessary  that  it  become  condensed  on  the  dorsum  of  the  pharynx,  and  this  is  secured  by  the 
ascent  of  its  caudal  fasciculi.  The  middle  constrictor  arises  from  the  hyoid  bar  close  to  the 
cranium  and  thence  radiates  to  the  dorsum  and  side  of  the  pharynx.  Its  most  rostral  fasciculi 
terminate  with  a  very  definite  edge  upon  the  pharyngeal  aponeurosis  at  some  distance  from 
the  pterygoid.  The  pharynx  has  a  maximum  length  from  the  hard  palate  to  the  beginning  of 
the  oesophagus,  of  32  mm.  The  greatest  breadth  of  its  lumen,  just  rostrad  of  the  hyoid  bars, 
is  13  mm.;  its  greatest  dorso-ventral  height,  12  mm. 

(Esophagus. —  From  its  emergence  between  the  oblique  portions  of  the  inferior  constrictors 
to  its  termination  in  the  first  stomach,  the  oesophagus  has  a  length  of  67  mm.,  of  which  10  mm. 
belong  to  its  abdominal  segment.  In  the  neck  and  mediastinum  to  the  point  where  the  aorta 
gains  its  left  side,  it  is  engaged  between  the  hypaxial  muscles  and  the  trachea,  and  is  dorso- 
ventrally  flattened  to  such  a  degree  that  its  lumen  is  reduced  to  a  transverse  slit  with  its  walls 
in  contact.  Its  greatest  breadth  is  4.5  mm.  Where  it  is  in  contact  with  the  aorta  on  the  left 


1  (>i>.  cit.,  p.  224.     Sec  also  to  the  same  effect  Carte  and  MacAlister,  op.  tit.,  p.  2  ir>. 


PLATE  XLIX. 


PLATE  LXIX. 


Balcenoptera  borealis. 

Fig.  1.     Tongue,  pharynx  and  larynx.     2|  X  natural  size. 

Fig.  2.     Base  and  diaphragmatic  surface  of  heart.     2f  X  natural  size. 

Fig.  3.     Cavities  of  the  atria.     2f  X  natural  size. 


1.  Tongue.  15. 

2.  Nasopharynx.  16. 

3.  Ridge  of  velum  corresponding  to  margin  of  tensor  palati.  17. 

4.  Free  edge  of  velum  and  arcus  palatopharyngeus.  18. 

5.  Concavity  of  dorsum  of  velum  palati.  19. 

6.  Epiglottis.  20. 

7.  Arytenoid    cartilage.  21. 

8.  Muscular  ridge.  22. 

9.  Oropharynx  into  which  opens  the  faucial  canal.  23. 

10.  Middle  constrictor.  24. 

11.  Inferior  constrictor.  25. 

12.  Thyroid  cartilage.  26. 

13.  (Esophagus.  27. 

14.  Trachea. 


Depression  of  floor  of  mouth  between  the  tongue  and  fauces. 

Aorta. 

Pulmonary  artery. 

Precava. 

Postcava. 

Coronary  sinus. 

Left  pulmonary  veins. 

Right  pulmonary  veins. 

Groove  of  right  pulmonary  artery. 

Reflection  of  serous  pericardium. 

Interventricular  furrow. 

Atrioventricular  furrow. 

Valve  of  the  foramen  ovale. 


[Memoirs  Am.  Mus.  Nat.  Hist. 


X.  S.,  Vol.  I,  Plato  >i 


, 


. 


15 


27 


Fig.  3. 


18 


3    -^_ 


Fig.  1. 


19 


BAL^NOPTERA  BOREALIS. 


S("HULTE,  SEI  WHALK.  435 

it  rather  abruptly  alters  its  shape,  the  left  margin  being  displaced  to  make  room  for  the  descend- 
ing aorta,  while  the  right  continues  straight.  Here  the  section  becomes  oval,  the  dorsoventral 
diameter  slightly  exceeding  the  transverse.  This  form  it  retains  until  it  begins  to  move  ventrad 
from  the  spine  as  it  approaches  the  diaphragm.  Here  its  section  is  circular  and  continues  so 
to  its  termination.  Its  diameter  is  3.5  mm.,  and  that  of  its  open  lumen  is  2  mm.  Here  also 
it  shows  the  presence  of  low  longitudinal  folds. 


THE  RESPIRATORY  PASSAGES. 
(Plates  XLIX,  Fig.  1,  and  LVI,  Fig.  2.) 

Nasal  fossa:  (by  John  D.  Kernan,  Jr.).  It  is  convenient  for  purposes  of  description  to 
distinguish  between  a  respiratory  passage  and  the  olfactory  region.  The  latter  forms  a  sub- 
spherical  diverticulum  from  the  dorsal  wall  of  the  respiratory  passage. 

The  respiratory  passage  is  tubular,  compressed  from  side  to  side,  and  is  directed  in  a  greater 
part  of  its  extent  obliquely  rostrad  and  dorsad.  At  the  margin  of  the  nasal  bone  its  direction 
changes,  swerving  dorsad  almost  vertically  to  the  narial  aperture.  This  passage  has  been 
divided  by  Weber  into  proximal  and  distal  portions,  the  nasal  and  naso-pharyngeal  ducts,  which 
correspond  approximately  to  the  precerebral  and  subcerebral  portions  of  de  Burlet  and  other 
authors.  The  rostral  limit  of  the  cerebral  cavity  in  this  fetus  lies  in  the  same  transverse  plane 
as  the  crista  semicircularis  so  that  the  whole  olfactory  region  belongs  to  the  pars  subcerebralis. 

The  precerebral  portion  is  about  half  as  long  as  the  subcerebral  portion.  It  is  more  com- 
pressed from  side  to  side  and  its  lateral  wall  presents  a  somewhat  complicated  relief.  This 
depends  upon  the  presence  of  the  "Spritzsack,"  an  oblique  diverticulum  which  attains  consider- 
able depth  above  the  level  of  the  osseous  paries.  Toward  the  interior  of  the  fossa  the  diverti- 
culum diminishes  in  depth,  becoming  a  shallow  furrow.  It  is  bounded  by  two  prominent  folds, 
which  with  the  diverticulum  have  a  spiral  course.  The  rostral  fold  at  the  narial  aperture  is 
broad  and  forms  the  lateral  lip  of  the  naris,  here  lying  dorsal  to  the  diverticulum  and  forming 
its  roof.  As  it  is  traced  into  the  respiratory  passage  it  diminishes  in  height  and  terminates  by 
passing  upon  the  septum.  It  thus  describes  a  spiral  from  the  lateral  to  the  mesal  wall  of  the 
passage,  crossing  the  rostral  paries  in  a  ventro-mesal  direction.  The  second  fold  belongs  to 
the  caudal  and  lateral  walls,  upon  which  it  descends  in  a  semicircular  course,  and  in  its  whole 
course  occupies  the  concavity  of  the  first  fold.  Toward  the  narial  aperture  it  forms  the  floor 
of  the  "Spritzsack."  It  owes  its  prominence  and  direction  to  the  cartilage  cupularis  and  forms 
a  cushion  upon  which  the  first  spiral  fold  is  molded,  and  against  which  it  becomes  firmly  coapted 
when  pressure  is  made  upon  the  narial  region  from  without.  The  arrangement  of  these  folds 
would  thus  seem  to  secure  the  effectual  closure  of  the  respiratory  passages  when  the  anima1 
is  submerged.  The  furrow  which  separates  these  two  folds  at  its  termination  upon  the  septum 
forms  a  shallow  fossa,  which  corresponds  in  position  to  the  open  groove  in  which  de  Burlet 
recognized  the  rudiment  of  Jacobson's  organ.  Ventral  to  the  nasal  bone  the  lateral  wall  of  the 
respiratory  passage  is  concave,  save  for  a  longitudinal  ridge  situated  midway  between  roof 
and  floor.  This  has  a  length  of  5  mm.,  a  breadth  of  1.5  mm.,  and  a  height  not  exceeding  1  mm. 
It  is  the  expression  of  a  ridge  in  the  cartilaginous  wall  of  the  nasal  fossa,  and  is  probably  the 
equivalent  of  the  naso-turbinal.  Its  ventral  margin  is  slightly  undermined  by  a  corresponding 


SCHULTE,  SEI  WHALE. 

sulcus.  The  remainder  of  the  respiratory  passage,  the  naso-pharyngeal  duct,  is  a  smooth-walled 
tubular  cavity  in  which  the  transverse  diameter  somewhat  exceeds  the  dorso- ventral. 

The  olfactory  region  communicates  with  the  respiratory  passage  by  a  narrow  slit-like  ori- 
fice between  the  broad  septum  nasi  mesad  and  the  crista  semicircularis  laterad.  On  the  removal 
of  the  septum,  the  crista  semicircularis  is  seen  as  a  sharp  falciform  margin  at  the  rostral  limit 
of  the  olfactory  region.  The  dorsal  cornu  extends  to  the  cribiform  plate;  the  ventral  cornu 
is  directed  ventrad  and  caudad,  becoming  continuous  with  the  maxillo-turbinal  which  forms  the 
ventral  limit  of  the  olfactory  region.  Lateral  to  the  crista  and  maxillo-turbinal  is  a  deep  narrow 
depression,  the  undivided  recessus  lateralis  inferior.  The  dorso-lateral  limit  of  this  recess  is 
formed  by  the  "Sammelleiste,"  (de  Burlet),  a  ridge  of  cartilage  covered  by  mucous  membrane 
extending  from  the  crista  semicircularis  to  the  lamina  transversalis  posterior,  which  forms  the 
caudal  limit  of  the  communication  between  the  olfactory  region  and  the  respiratory  passage. 
The  space  above  the  "  Sammelleiste  "  is  divided  by  the  vertical  ridge  of  the  first  ethmo-turbinal 
into  a  caudal  recessus  posterior  and  a  rostral  depression,  the  recessus  lateralis  superior.  This, 
as  its  name  implies,  is  a  laterally  directed  diverticulum  of  the  olfactory  region;  its  fundus,  how- 
ever, is  prolonged  caudad  into  a  deep  recess  on  the  lateral  aspect  of  the  first  ethmo-turbinal. 
In  its  depth  are  visible  two  diminutive  oblique  fronto-turbinal  ridges.  Of  these  the  second 
is  considerably  the  smaller  and  is  wholly  concealed  in  median  view  by  the  first  ethmo-turbinal. 

The  recessus  posterior  or  ethmo-turbinal  region  is  smaller  than  the  recessus  lateralis.  Its 
rounded  fundus  occupies  the  cupula  posterior  of  the  nasal  capsule.  Its  orifice  is  contracted 
and  bounded  rostrad  by  the  first  ethmo-turbinal,  ventrad  by  the  lamina  terminalis,  dorsad  by 
the  cribiform  plate,  caudad  by  the  free  edge  of  the  mesal  wall  of  the  cupula  posterior.  Its 
lateral  wall  shows  the  presence  of  a  well  developed  third  ethmo-turbinal,  between  which  and  the 
first  of  the  series  a  rudimentary  second  can  be  detected. 

Larynx. —  The  larynx  conforms  so  closely  to  the  descriptions  of  previous  writers  that  it 
here  requires  but  passing  notice.  The  elongated  epiglottis  rises  high  into  the  pharynx,  its 
enlarged  extremity  lying  above  the  level  of  the  velum.  Rostrad  it  is  connected  to  the  hyoid 
by  a  prominent  hyo-epiglottic  fold  of  mucous  membrane  (Turner).  On  its  caudal  surface  I 
could  find  no  trace  of  a  Czermak's  cushion  such  as  Turner  describes.  This  surface  is  deeply 
grooved  axially  and  the  lips  of  the  groove  are  elevated  to  high  triangular  folds,  which  passing 
lateral  to  the  free  rostral  margins  of  the  arytenoids,  diminish  in  height  and  are  attached  to  their 
lateral  surfaces.  The  arytenoids  are  high  and  broad,  but  very  thin  and  leaf-like.  Their  dorsal 
margins  are  united  in  about  half  their  extent,  the  ventral  free  and  boldly  curving.  The  free 
margins  were  closely  approximated  in  this  foetus,  but  not  adherent  and  fitted  in  between  the 
high  ary-epiglottic  folds  described  above.  There  were  no  vocal  cords.  The  muscles  and  the 
cricoid  cartilage  I  did  not  examine. 

Thyroid  cartilage. —  The  thyroid  cartilage  consists  of  two  symmetrical  halves  which  have 
not  yet  fused  in  the  median  line,  but  are  closely  united  by  a  narrow  plate  of  connective  tissue. 
In  general  shape  it  resembles  Carte  and  MacAlister's  '  figure  much  more  closely  than  Turner's,2 
but  departs  from  both  considerably.  The  lateral  margin  is  distinctly  concavo-convex  and  serves 
to  give  attachment  to  the  inferior  constrictor.  Its  length  is  17  mm.  The  mesal  margin,  6.5 
mm.  in  length,  was  for  rather  more  than  half  of  this  distance  united  with  its  fellow.  Caudad 


1  Carte  and  MacAlister,  op.  cit.,  pi.  v,  fig.  5. 
•  Turner,  op.  rit.,  pi.  viii,  fig.  36. 


SCHl'LTK,  SKI  \VIIALE. 


Fig.  ">.  Thyroid  r;irlilagi-.  '1  /  lut.  size.  1, 
Origin  of  thyrohyoidcus.  2,  Origin  of  inferior 
constrictor.  3,  Insertion  of  sterno-thyrnideus. 
4,  Insertion  of  eirco-thyroideiis.  .",.  Origin  of 
muscle  of  laryngeal  pouch. 


there  is  a  deep  notch  between  the  diverging  borders.  The  rostral  margin  passes  laterad  and 
rostrad  in  a  slightly  concave  course  to  the  anterior  cornu, 
which  is  but  a  pronounced  angle  at  the  junction  of  the 
rostral  and  lateral  borders.  The  caudal  margin  is  deeply 
concave  between  the  great  posterior  cornu  and  a  mesal 
process  which  marks  its  junction  with  the  median  border. 
To  this  process  and  the  whole  caudal  margin  is  attached 
the  muscle  of  the  laryngeal  pouch  (M.  thyreo-arytenoideus, 
Dubois  ').  The  posterior  cornu  is  rounded,  directed  caudad 
with  a  mesal  concavity  and  has  a  length  of  11.5  mm. 
Mesad  it  gives  origin  to  the  crico-thyroid,  dorsad  to  the  in- 
ferior constrictor.  The  thyro-hyoid  arises  from  the  anterior 
cornu,  the  lateral  half  of  the  rostral  border  and  the  adjacent 
ventral  surface.  The  sterno-thyroid  has  a  wide  insertion 
into  the  ventral  surface  and  lateral  margin  in  the  angle 
between  the  attachments  of  the  thyro-hyoid  and  inferior  constrictor  muscles. 

Laryngeal  sac. —  The  laryngeal  sac  in  this  foetus  has  a  length  externally  of  18  mm.,  a  breadth 
of  1 1  mm.  Its  wall  is  very  thick,  its  lumen  a  transverse  slit.  This  has  an  elongated  communi- 
cation with  the  larynx  through  the  gap  in  the  cricoid  and  between  the  bases  of  the  arytenoids. 
Its  dorsal  wall  is  attached  in  its  whole  length,  rostrad  to  the  cricoid,  caudad  to  the  tracheal  rings, 
so  that  its  fundus  is  not  free  as  in  Dubois's  figure  of  Balaena.  This  connection  is  by  muscular 
fasciculi.  The  muscle  of  the  pouch,  which  Dubois  considers  to  be  the  thyreo-arytenoideus 
on  account  of  its  innervation  by  the  inferior  laryngeal  nerve,  arises  from  the  caudal  margin 
of  the  thyroid  cartilage  and  the  ventral  borders  of  its  posterior  cornua  in  their  whole  length. 
The  superficial  fasciculi  radiate  from  the  mesal  process  of  the  cartilage;  the  rostral  are  trans- 
verse and  disappear  beneath  the  cricothyroid  muscles;  the  intermediate  are  oblique  and  turning 
round  the  sides  reach  the  cricoid  cartilage;  the  caudal  are  nearly  longitudinal  and  insert  upon 
the  rings  of  the  trachea  as  far  caudad  as  the  origin  of  the  right  eparterial  bronchus.  While  many 
surmises  have  been  made  as  to  the  function  of  this  sac,  I  do  not  remember  to  have  seen  it  sug- 
gested, that  by  its  contraction  and  relaxation  during  submergence,  a  circulation  of  air  in  the 
wide  trachea  and  bronchi  might  be  set  up,  which  would  favor  the  absorption  of  oxygen  by  bring- 
ing the  air  in  these  passages  more  rapidly  into  contact  with  the  respiratory  membrane  than 
could  be  done  by  the  usual  diffusion  currents. 

Trachea. —  The  trachea  is  short  and  wide;  dorsally  it  is  flattened  against  the  oesophagus. 
Its  external  dimensions  are  as  follows:  length  9.5  mm.;  breadth,  rostral  to  right  apical  bronchus, 
9  mm.;  caudal  to  same  8  mm.;  dorsoventral  diameter  6  mm.;  length  to  origin  of  right  apical 
bronchus,  6  mm.  As  in  the  other  members  of  the  order,  the  cartilaginous  wall  is  very  com- 
plete, the  rings  being  close-set  and  separated  only  by  narrow  intervals.  The  rostral  ones  as 
Dubois  -  and  Muller  3  have  observed  are  continuous  with  the  lamina  of  the  cricoid  cartilage. 
Yentrally  the  ends  of  these  rings  are  widely  separated,  the  wall  being  completed  by  membrane. 
This  condition  obtains  in  almost  the  whole  extent  of  the  laryngeal  sac.  Rostrad  the  membrane 


1  Dubois,  Bug.     In  Weber's  Studien  fiber  Saugethiere,  II,  p.  101  D.  Jena,  1886. 
-  Dubois,  E.,  op.  cit.,  p.  92. 
3  Muller,  O.,  op.  cit.,  p.  197. 


Oj-  I  HE 
H    UNIVEKi 

Vv    OH 


438  SCHULTE,  SEI  WHALE. 

is  continuous  with  the  cricoid  cartilage,  between  the  ventral  bars  of  which  the  sac  communicates 
with  the  larynx.  Caudad  the  membrane  diminishes  in  width  terminating  by  a  pointed  extrem- 
ity at  the  level  of  the  origin  of  the  right  apical  bronchus.  From  the  end  of  the  membrane  a 
shallow  groove,  convex  to  the  right,  is  continued  to  the  angle  of  the  bifurcation.  Along  this 
groove  the  ends  of  the  tracheal  cartilages  are  in  contact  but  not  fused,  so  that  in  this  foetus  there 
are  no  complete  rings.  The  number  of  those  intervening  between  the  membrane  and  the  bifur- 
cation is  only  three;  of  those  with  ends  widely  separated  by  the  membrane,  five.  This  condi- 
tion of  incomplete  rings  throughout  agrees  with  Dubois'  statement  for  Mystacoceti  in  general. 
On  the  other  hand  in  B.  antipodum  (Beauregard  and  Boulart ')  there  are  only  three  rings  which 
are  not  closed  ventrally  and  in  B.  musculus  Miiller  finds  that  out  of  seven  or  eight  rings 
only  five  are  incomplete.  As  regards  B.  rostrata  (=  acuto-rostrata)  Carte  and  MacAlisterV' 
statement  is  incomplete,  but  their  description  I  take  as  meaning  that  at  least  one  complete 
ring  is  present.  Turner3  describes  in  B.  sibaldii  three  "somewhat  irregularly  formed  carti- 
laginous hoops  immediately  above  the  bifurcation."  In  the  illustration  of  his  plate  viii,  fig.  37, 
the  ventral  ends  appear  in  contact  but  not  fused.  On  the  left  side  there  are  five  free  tips  abut- 
ting on  the  membrane,  on  the  right  six,  one  being  a  small  bit  of  cartilage  opposite  the  tracheal 
bronchus.  In  the  same  species  Beauregard  and  Boulart  describe  five  open  rings.  The  first 
and  second  are  connected  to  the  right  of  the  median  line,  and  similarly  the  third  and  fourth 
to  the  left. 

Bronchi. —  Only  their  extra-pulmonary  portions  are  here  considered.  The  tracheal,  or  right 
apical  bronchus,  is  given  off  just  caudad  of  the  apex  of  the  lung  and  immediately  enters  its 
substance,  the  lung  filling  the  angle  between  it  and  the  right  stem-bronchus  so  completely,  that 
only  along  its  lateral  aspect  can  it  be  said  to  be  extra-pulmonary,  and  here  it  is  lodged  in  a  deep 
groove  in  the  lung.  Its  diameter  is  3  mm.  The  bifurcation  is  concealed  by  the  arch  of  the 
aorta.  The  stem-bronchi  diverge  slowly  and  are  in  contact  by  their  mesal  walls  as  far  as 
the  level  of  the  right  pulmonary  artery.  The  right  then  curves  strongly  dextrad  and  enters  the 
lung  under  cover  of  the  artery,  having  the  pulmonary  veins  below  it  at  the  turn,  though  the 
upper  vein  soon  passes  to  its  ventral  surface.  The  left  primary  bronchus  takes  a  longer  and 
more  oblique  course  to  the  hilum,  passing  dorsal  to  the  right  pulmonary  artery.  At  its  entrance 
the  left  artery  is  rostral  to  it  as  is  also  the  left  upper  vein,  the  remaining  two  pulmonary  veins 
on  this  side  are  caudal  to  it.  The  right  primary  bronchus  measures  4.5  mm.  in  diameter,  the 
left  4  mm. 

THE  THORAX. 
(Plates  XLIX,  Figs.  2  and  3,  L.} 

The  thorax  is  broad  and  deep,  approaching  the  keeled  form  ventrally,  the  dorsoventral 
diameter  apparently  exceeding  the  transverse,  though  in  consequence  of  the  distortion  of  its 
right  side  but  little  reliance  can  be  placed  upon  its  proportions.  The  rostral  closure  of  the 
cavity,  inside  the  arch  of  the  first  rib,  is  largely  effected  by  the  great  rectus-scalene  muscle- 
complex,  between  the  diverging  arms  of  which  the  dome  of  the  pleura  is  embraced,  there  being 


1  Beauregard  and  Boulart.    Jour,  de  1'Anat.  et  de  la  Phys.,  T.  18,  p.  623. 

2  Carte  and  MacAlister,  op.  cit.,  p.  243. 

3  Turner,  W.,  op.  at.,  p.  236. 


SCHULTE,  SEI  WHALE.  439 

left  beyond  the  dome  a  pyramidal  space  containing  fat.  The  existence  of  this  space  would 
suggest  that  the  recession  of  the  apices  of  the  lung  was  due  to  intrinsic  causes,  and  not  primarily 
to  the  shortening  of  the  neck  or  the  great  development  of  muscles  in  this  situation.  Ventrally 
are  the  sternohyoid  and  sternothyroid  muscles;  the  triangular  interval  between  them  and  the 
scalene  gives  passage  to  the  great  vessels,  vagus  and  phrenic  nerves,  and  is  covered  superficially 
by  dense  cervical  fascia.  The  space  thus  defined  though  large  is  no  more  than  adequate  for 
the  passage  of  the  oesophagus,  trachea  and  laryngeal  sac.  Caudad  the  diaphragm  is  attached 
ventrally  between  the  ends  of  the  sixth  ribs,  thence  ascending  in  the  midline  to  the  fourth  space. 
To  this  ascending  slope  is  attached  the  pericardium.  From  the  postcava  the  diaphragm  slopes 
dorsad  and  caudad  attaining  its  most  caudal  point  at  about  the  middle  of  the  last  rib.  This 
division  of  the  diaphragm  into  two  sharply  denned  planes  meeting  at  an  angle,  appears  to  be 
a  fcetal  condition  dependent  upon  the  unexpanded  condition  of  the  lungs. 

Pleurce. —  The  dome  of  the  pleura  is  lodged  in  the  interval  of  the  scalene-rectus  complex, 
rising  high  in  the  first  space,  but  not  reaching  the  caudal  margin  of  the  first  rib.  Here  the  pos- 
terior thoracic  artery  and  accompanying  vein  cross  its  summit.  The  reflection  of  the  pleura 
dorsally  follows  the  margin  of  the  rectus  capitis  anticus  major,  overlapping  its  ventral  surface 
increasingly  caudad,  and  this  more  on  the  right  side  than  on  the  left,  to  reach  the  beginning 
of  the  descending  aorta.  From  this  point  the  sacs  of  the  two  sides  are  in  contact  and  their 
reflections  cross  the  aorta  obliquely,  passing  from  its  right  to  its  left  side  as  they  proceed  caudad. 
On  the  diaphragm  they  are  separated  by  the  pericardial  attachment,  coming  together  again 
upon  the  ventral  thoracic  wall  and  so  continuing  to  the  first  space,  there  passing  transversely 
laterad  to  the  posterior  thoracic  artery  along  which  they  ascend  to  the  dome.  On  account 
of  the  obliquity  of  the  diaphragm  the  pleura  extends  farther  caudad  dorsally  than  ventrally,  and 
reaches  farthest  caudad  in  the  angle  of  the  diaphragmatic  origin,  between  its  attachment  to  the 
last  rib  and  its  lateral  crus.  This  point  is  at  about  the  middle  of  the  rib,  and  is  distant  76  mm. 
from  the  dome  of  the  pleural.  Ventrally  in  the  midline  the  extent  of  the  pleura  is  43  mm.  and 
in  the  approximate  dorsal  midline,  along  the  aorta  from  the  beginning  of  its  descending  portion 
to  the  hiatus  aorticus,  it  is  46  mm.  The  pleural  sacs  are  widely  separated  at  the  rostral  thoracic 
aperture  by  the  great  size  of  the  mediastinal  complex  as  it  passes  into  the  neck,  especially  the 
trachea  and  the  laryngeal  sac.  A  well  defined  ligamentum  latum  descends  from  each  hilum  to 
the  diaphragm. 

Lungs. —  The* lungs  are  long  and  rather  narrow,  attaining  their  greatest  vertical  breadth 
at  the  junction  of  pericardium  and  diaphragm,  where  an  angle  is  formed  in  the  ventral  margin. 
Beyond  this  they  narrow  slowly  by  the  retreat  of  the  ventral  margin  and  are  abruptly  truncated 
caudad.  As  the  ventral  margin  turns  here  to  an  approximately  transverse  course  a  small  angular 
projection  is  formed,  which  is  the  most  caudal  point  of  the  lung.  Mesal  to  this  the  margin 
ascends  slightly  cephalad  before  becoming  transverse.  From  the  angle  at  the  pericardio- 
diaphragmatic  junction  caudad  the  margin  is  very  sharp  and  is  formed  by  a  narrow  fold  of 
visceral  pleura,  into  which  pulmonary  tissue  has  not  extended  and  which  is  translucent  when 
held  to  the  light.  The  rostral  portion  of  the  ventral  margin  is  thick  and  rounded,  extending 
to  the  apex  with  a  sinuous  course.  At  the  sides  of  the  pericardium  it  is  concave,  as  is  also  the 
mediastinal  surface,  while  rostrad,  beyond  the  pericardium  both  margin  and  surface  become 
convex.  The  dorsal  border  is  thick  and  massive  filling  the  costovertebral  groove.  It  is  straight 
except  at  its  beginning  and  end  where  it  curves  ventrad  to  a  slight  degree.  The  surface  of  the 


440  SGHULTE,  SEI  WHALE. 

lung  is  smooth  and  uniform  showing  no  trace  of  fissures  or  of  lobulation.  The  diaphragmatic 
surface  is  separated  from  the  mediastinal  by  a  massive  ridge,  which  fills  the  shallow  pericardio- 
diaphragmatic  groove.  On  the  costal  surface,  extending  from  apex  to  the  projecting  angle  of 
the  caudal  margin  is  a  low  sagittal  ridge  which  divides  this  surface  into  dorsal  and  ventral  por- 
tions. It  corresponds  to  the  angles  of  the  ribs.  The  foregoing,  while  applicable  to  both  lungs, 
is  based  more  particularly  upon  the  left;  the  right  in  consequence  of  the  bend  of  the  thorax 
is  somewhat  flattened  caudally  and  bears  very  deep  impressions  of  the  ribs  on  its  costal  surface. 
The  left  lung  has  a  length  of  59  mm.  Its  greatest  vertical  breadth,  at  the  pericardio-diaphrag- 
matic  angle  is  22  mm.;  its  greatest  thickness,  at  the  same  point,  16  mm.  The  right  lung- 
measures  55  mm.  in  length,  25  mm.  in  breadth,  14  in  thickness;  but  these  dimensions,  especially 
the  last  two,  are  altered  by  the  deformation  of  the  lung.  The  apices  are  blunt  and  are  grooved 
by  the  posterior  thoracic  artery  and  the  accompanying  vein,  which  cross  them  in  a  dorso-lateral 
direction.  The  subclavian  vessels  in  their  arch  over  the  first  rib  do  not  come  in  contact  with 
the  apices  of  the  lungs;  the  thoracic  portion  of  the  left  artery  is  however  in  contact  with  the 
mediastinal  surface  of  the  left  lung.  The  interval  between  the  subclavian  arch  and  the  apex 
of  the  lung,  must  in  my  judgment  be  ascribed  to  a  reduction  of  the  lung  itself,  coincident  with 
and  in  excess  of  the  skeletal  shortening  affecting  the  cervical  and  upper  thoracic  regions. 

Mliller  l  in  the  course  of  an  elaborate  study  of  the  lungs  of  aquatic  mammals  has  described 
those  of  Balcenoptera  musculus.  A  comparison  with  his  figures  shows  a  general  close  resemblance 
to  the  conditions  present  in  this  fcetus,  but  in  his  specimen  the  apex  is  more  deeply  grooved. 
His  seventeenth  figure  shows  a  left  lung  dorso-ventrally  flattened,  the  right  having  a  well 
marked  ridge,  which  probably  corresponds  to  the  angles  of  the  ribs,  in  contrast  to  the  flattened 
right  lung  and  more  smoothly  rounded  ridge  on  the  costal  surface  of  the  left  lung  in  this  fcetus. 
Evidently  the  question  of  preservation  and  in  particular  the  position  of  the  foetus  in  its  contain- 
ing jar  is  a  factor,  which  ought  not  to  be  lost  sight  of  in  considerations  upon  the  form  and  surface 
relief  of  the  viscera. 

The  mediastinal  surface  is  separated  from  the  diaphragmatic  by  a  well  defined  ridge  which 
is  in  apposition  with  the  fat  pad  of  the  pericardio-diaphragmatic  junction.  Both  surfaces  are 
concave,  the  mediastinal  strongly  so  when  it  comes  to  be  applied  to  the  pericardium  ventral  to 
the  hilum.  Rostrad  it  becomes  convex,  on  the  left  side  presenting  a  gutter  for  the  termination 
of  the  aortic  arch,  from  which  ascends  towards  the  apex  a  shallow  subclavian  groove.  On  the 
right  side  in  this  surface  is  a  deep  notch-like  groove  extending  to  the  apex,  which  lodges  the 
tracheal  bronchus.  The  depth  of  the  groove  seems  to  have  been  exaggerated  and  its  angu- 
larity occasioned  by  the  torsion  of  the  fcetus  to  the  right.  The  point  of  entry  of  the  bronchus 
is  4  mm.  from  the  apex.  The  hilum  of  the  left  lung  has  a  length  of  15  mm.  Its  upper  extremity 
is  17  mm.  from  the  apex  and  7  mm.  from  the  ventral  margin,  its  lower  11  mm.  from  this  margin. 
On  the  right  side  the  entrance  of  the  tracheal  bronchus  is  independent  of  the  hilum,  with  which 
it  is  connected  only  by  a  continuous  pleural  reflection.  Between  the  two  ventrally  and  the 
shallow  groove  of  the  precava  is  a  prominence  of  the  mediastinal  surface.  The  main  hilum  has 
a  length  of  18  mm.  and  its  rostral  end  is  12  mm.  from  the  apex. 

Pericardium. —  The  pericardium  is  broadly  exposed  between  the  ventral  margins  of  the 
lungs  and  is  separated  from  the  thoracic  wall  only  by  the  sinus  costomediastinales  of  the  pleurse. 

1  Milller,  O.     Untersuchungen  iiber  die  Veranderungen  welche  die  Respirationsorgane  der  Saugetiere  durch  die  Anpassung  an  das 
Leben  in  Wasser  erlitten  haben.     Jena.  Zeitschr.  f.  Naturw.,  Bd.  32.  1898. 


PLATE  L. 


PLATE  L. 


Fig.  1.    Thoracic  viscera,  ventral  view. 
Fig.  2.    Thoracic  viscera,  ventral  view. 

1.  Thyroid  cartilage. 

2.  Muscle  of  tracheal  sac. 

3.  M.  cricothyroideus. 

4.  Phrenic  nerve. 

5.  Internal  jugular  vein. 

6.  Common  carotid  artery. 

7.  Thyroid  gland. 

8.  Superior  intercostal  vein. 

9.  Posterior  thoracic  artery. 
10.     Precava. 

11  Lung. 

12.  Thymus. 

13.  Pulmonary  artery. 

14.  Right  atrium. 

15.  Left  atrium. 

16.  Right  ventricle. 

17.  Left  ventricle. 


Balamoptera  borealis. 

• 

Twice  natural  size. 

The  heart  and  great  veins  have  been  removed.     Twice  natural  s 

18.  Pericardial  fat  pad. 

19.  Diaphragm. 

20.  Right  brachiocephalic  artery. 

21.  Left  common  carotid  artery. 

22.  Left  subclavian  artery. 

23.  Arch  of  the  aorta. 

24.  Stump  of  aorta. 

25.  Glandular  body,  possible  parathyroid. 

26.  Reflection  of  serous  pericardium. 

27.  Upper  left  pulmonary  vein. 

28.  Lower  left  pulmonary  vein. 

29.  Middle  left  pulmonary  vein. 

30.  Right  pulmonary  artery. 

31.  Right  pulmonary  veins. 

32.  Postcava. 

33.  Cut  edge  of  fibrous  pericardium. 


Memoirs  Am.  Mus.  Nat.  Hist. 


X.  S.,  Vol.  I,  Plate  L. 


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SCHl'LTK,  SKI  WHALK.  441 

Above  its  fibrous  layer  blends  with  the  adventitia  of  the  precava,  aorta  and  pulmonary  artery. 
Below  it  is  very  broadly  attached  to  the  ventral  slope  of  the  diaphragm.  The  pericardium  attains 
its  greatest  breadth  at  about  its  middle  and  thence  contracts  somewhat  towards  the  diaphragm. 
The  resulting  groove  at  their  junction  is  filled  by  a  large  subpleural  fat  pad,  which  is  continuous 
across  the  median  line,  but  attains  its  greatest  size  at  the  sides.  While  this  compensates  in 
large  part  for  the  contraction  of  the  pericardium,  it  does  not  do  it  so  completely  but  that  the 
lung  presents  a  ridge  as  the  boundary  between  its  phrenic  and  mediastinal  surfaces. 

Not  only  is  the  pericardiac-phrenic  adhesion  very  extensive,  but  a  further  evidence  of 
crowding  in  this  region  is  offered  by  the  serous  layer  of  the  pericardium,  in  which  the  oblique 
sinus  has  been  obliterated.  The  reflection  on  the  dorsal  wall  after  passing  from  the  right  side 
of  the  precava  to  that  of  the  postcava  sweeps  ventrad  to  the  latter,  and  there  passes  directly 
to  the  lower  left  pulmonary  vein,  which  is  just  to  the  left  and  rostrad  of  the  postcava  as  it  enters 
the  atrium.  The  line  of  reflection  then  ascends  to  the  upper  left  pulmonary  vein,  there  turning 
obliquely  to  the  right  to  reach  the  precava.  In  the  area  thus  exposed  are  situated  the  pulmon- 
ary veins  of  which  there  are  three  on  the  left,  a  small  intermediate  one  entering  the  auricle  inde- 
pendently. To  the  right  of  the  pulmonary  veins  is  the  large  obliquely  directed  right  pulmonary 
artery,  which  grooves  the  dorsum  of  the  right  atrium  between  the  caval  veins.  The  pulmonary 
artery  and  aorta  are  enclosed  as  usual  in  a  common  tube  of  serous  pericardium.  The  circular 
sinus,  on  account  of  their  large  size  and  the  rostro-caudal  compression  of  the  heart,  is  of  small 
dimensions. 

Heart. —  The  heart  is  markedly  contracted  in  the  diameter  corresponding  to  the  longi- 
tudinal axis  of  the  foetus  and  markedly  broadened  from  side  to  side.  Its  greatest  breadth  is 
31  mm.;  from  base  to  apex  it  measures  29  mm.;  its  base  has  a  rostro-caudal  height  of  19  mm. 
That  this  shape  of  the  heart  stands  in  relation  to  the  shortening  of  the  ventral  wall  of  the  thorax 
and  is  one  of  the  effects  of  adaptation  of  the  body-form  to  aquatic  life,  has  been  demonstrated 
by  Miiller  on  the  basis  of  unusually  abundant  comparative  material.  He  has  also  found  further 
consequences  of  these  factors  in  the  extensive  adhesion  of  the  pericardium  to  the  diaphragm 
and  the  suppression  of  the  lobation  of  the  lungs.  The  long  axis  of  the  heart  itself  tends  further 
to  approach  more  or  less  a  dorso-ventral  direction.  In  this  foetus  it  not  only  deviates  slightly 
to  the  left  —  the  faint  notch  at  the  distal  end  of  the  interventricular  furrow  was  situated  about 
3  mm.  to  the  left  of  the  midline  —  but  it  has  in  addition  a  distinct  inclination  caudad,  correspond- 
ing to  the  slope  of  the  ventral  plane  of  the  diaphragm.  The  heart  itself  has  undergone  but 
the  slightest  degree  of  rotation  upon  its  axis,  and  the  areas  occupied  by  the  ventricles  on  its 
phrenic  and  ventral  surfaces  are  subequal.  This  may  be  expressed  in  terms  of  the  right  ventricle, 
the  ventral  surface  of  which  at  its  middle  has  a  breadth  of  10  mm.,  the  phrenic  9  mm.  Simi- 
larly the  phrenic  surface  of  the  left  ventricle  slightly  exceeds  the  ventral.  The  right  and  left 
borders  of  the  heart  are  equally  acute  and  almost  symmetrical  in  position.  By  reason  of  the 
great  size  of  the  pulmonary  artery  and  the  aorta,  the  interauricular  notch  is  very  wide  and 
deep,  and  the  atrial  septum  reduced  to  little  more  than  the  narrow  limbus  of  the  fossa  ovalis 
and  its  valve.  The  postcava  enters  the  right  atrium  far  to  the  left  in  reference  to  the  precava. 
The  latter  is  marked  at  its  entrance  ventrad  by  a  deep  veno-atrial  angle,  which  forms  the  start- 
ing point  of  the  sulcus  limitans.  This  can  be  followed  only  about  two  thirds  of  the  way  to 
the  postcava.  Between  the  cavae  the  wall  of  the  atrium  is  inflected  by  a  deep  oblique  groove 
which  lodges  the  right  pulmonary  artery,  occasioning  an  ental  prominence  approximately  in  the 


442  SCHULTE,  SET  WHALE. 

position  of  the  intervenous  tubercle  (Loweri).  Entally  the  atrio-ventricular  rings  are  very 
prominent  and  from  them  many  muscular  trabeculse  radiate  to  the  walls  of  the  auricles,  which 
by  their  caudal  margins  overhang  and  conceal  the  atrio-ventricular  sulcus.  This  holds  true 
only  of  the  ventral  and  lateral  margins  of  the  venous  ostia;  mesad  and  dorsad  the  rings  sink 
to  the  level  of  the  respective  walls  of  the  heart.  The  right  auricle  has  a  crista  terminalis  con- 
forming in  extent  to  the  sulcus  of  the  same  name  ectally.  From  this  trabeculse  extend  in  an 
irregular  manner  to  the  wall  of  the  auricle.  On  the  left  side  there  was  an  arched  ridge  from 
beside  the  upper  pulmonary  vein,  bifurcating  laterally  and  being  attached  to  the  atrio-ventri- 
cular ring  at  two  points.  From  this  also  trabeculse  were  given  off.  On  neither  side  had  the 
musculature  of  the  auricle  anything  approaching  a  pectinate  arrangement. 

The  right  atrium  is  noteworthy  for  the  total  suppression  of  the  right  sinus  valve.  As  in 
other  Cetacea  there  is  no  Eustachian  and  no  Thebesian  valve.  The  large  orifice  of  the  coronary 
sinus  has  however  a  sharp  and  slightly  overhanging  margin  in  the  caudal  half  of  its  contour. 
The  limbus  fossae  ovalis  is  a  well  defined  but  narrow  frame  to  the  fossa,  which  is  placed  immedi- 
ately caudad  of  the  intervenous  tubercle.  The  atrial  septum  as  has  been  said  is  small  and  the 
atria  diverge  widely  ventrad,  as  in  reptiles,  and  for  the  same  cause,  the  great  size  of  the  vessels 
to  be  accommodated  between  them.  The  valve  of  the  fossa  ovalis  is  highly  peculiar  in  that  it 
is  attached  in  its  entire  circumference  to  the  limbus  and  has  no  free  edge.  It  protrudes  in  the 
left  atrium  as  a  long  funnel  or  cornucopia  with  a  fenestrated  fundus.  Knox  l  described  it  in 
the  heart  of  a  foetal  Balcena  mysticetus  as  "a  membranous  sac,  the  size  of  a  full-sized  thimble, 
presenting  at  the  bottom  a  delicate  reticulated  network,  and  projecting  into  the  left  auricle." 
Turner 2  from  whom  this  quotation  is  borrowed  describes  the  structure  in  a  foetus  of  B.  musculus 
measuring  19  ft.  6  in.  in  length.  "In  the  interauricular  septum  an  almost  circular  foramen 
readily  admitting  five  extended  digits  was  situated.  Surrounding  this  opening  and  attached 
to  its  edge,  a  loose,  membranous,  annular  fold,  formed  by  a  duplication  of  the  endocardium  was 
seen.  When  put  on  the  stretch  it  projected  into  the  auricle,  and  the  projecting  border  was  free 
and  pierced  with  large  fenestrse.  Although  this  fold  was  situated  in  the  right  auricle,  when  I 
opened  into  that  cavity,  yet  it  could  without  difficulty  be  passed  through  the  foramen  into  the 
left  auricle.  At  the  attached  border,  again,  the  membrane  was  almost  entire,  and  most  perfect  in 
its  anterior,  external  and  posterior  portions,  where  the  depth  from  the  attached  to  the  free  margin 
was  four  inches."  In  this  foetus  the  valve  measures  7  mm.  in  length.  The  foramen  at  the  limbus 
6  mm.  by  4  mm.  The  funnel  depended  completely  free  into  the  left  atrium  and  was  not  main- 
tained in  position  by  reticnacula,  save  that  near  its  base  ventrally  a  very  small  fold,  like  a  minute 
frenulum,  connects  it  with  the  wall  of  the  atrium.  In  a  much  larger  heart  from  a  foetal  Megaptera 
preserved  in  spirits  by  Mr.  Andrews,  the  valve  had  the  same  general  character,  but  had  con- 
tracted adhesions  ventrally  with  the  atrial  wall  for  about  one  third  its  length.  These  were  not 
sufficient  to  prevent  the  valve  from  being  inverted  into  the  right  auricle,  where  it  was  found  folded 
and  collapsed  as  in  Turner's  specimen.  In  the  adhesions  at  the  base  of  the  valve  may  be  seen 
the  initiation  of  a  process  of  closure,  which  appears  to  differ  from  that  known  in  other  vertebrates. 
Were  these  adhesions  to  continue  distad  to  the  fundus  of  the  valve,  its  ventral  portion  would 
become  fused  with  the  atrial  wall  in  its  whole  extent.  The  remainder  would  then  occupy  a  posi- 


1  Knox,  R.     Catalogue  of  Anatomical  Preparations  of  the  Whale.     Edinburgh,  1838. 

-  Turner,  Wm.     An  Account  of  the  great  finner  whale  stranded  at  Longniddy  (Balcenoplera  Sibaldii).    Trans.  Roy.  Soc.  Edin., 


1872. 


SCHULTE,  SEI  WHALE.  443 

tion  on  the  left  of  the  septum  similar  to  that  of  the  usual  valve  of  placentals,  from  which  it  would 
differ  in  its  great  length  and  in  its  extensively  fenestrated  margin,  which  would  be  attached 
to  the  atrial  wall  by  the  numerous  strands  intervening  between  the  fenestrse.  The  establish- 
ment of  subsequent  adhesions  would  effect  the  definitive  closure  of  the  foramen.  The  peculi- 
arity of  the  valvula  here  consists  primarily  in  its  ballooning  into  the  left  auricle,  a  condition 
recorded  by  Rose l  only  in  Terrapene,  and  it  may  be  noted  in  passing  that  at  the  fundus  the  sep- 
tum in  this  form  was  very  thin  in  places  and  the  separation  of  the  atria  was  effected  only  by 
endocardium.  Though  actual  communications  are  not  formed  in  reptiles,  the  condition  is 
certainly  strikingly  analogous  to  the  funnel-like  valve  of  the  Cetacea  with  its  fenestrated  fundus. 
A  second  peculiarity,  though  one  shared  by  birds,  monotremes  and  marsupials  (Rose)  is  in  the 
site  and  multiplicity  of  the  perforations  of  the  septum  primum.  This  maintains  itself  in  its 
upper  segment  where  the  foramen  ovale  secundum  of  placentals  is  established,  which  so  comes 
later  to  be  covered  on  the  right  by  the  crescentic  downgrowth  of  the  septum  secundum.  Here 
the  perforations  are  small  and  multiple  and  occupy  the  middle  of  the  septum  primum.  In 
consequence,  when  the  septum  secundum  develops  on  the  right  and  comes  to  be  amalgamated 
with  the  primum,  the  latter  has  no  free  edge  but  is  attached  in  its  whole  circumference  per- 
mitting communication  between  the  atria  by  way  of  its  fenestrated  middle.  In  birds,  mono- 
tremes and  marsupials  the  perforations  are  closed  by  proliferation  of  the  endocardium,  and 
there  is  plain  evidence  of  the  embryonic  process  in  the  structure  of  the  valve  of  the  adult  (Rose), 
which  is  marked  by  a  reticulum  of  ridges  with  intervening  thinner  areas.  In  the  adult  Cetacean 
I  have  not  found  in  the  descriptions  of  the  atrial  septum  a  record  of  this  type  of  structure.  In 
view  of  the  adhesions  ventrally  at  the  base  of  the  valve,  I  have  ventured  to  suggest  the  mode  of 
closure  outlined  above.  It  is  possible  to  see  in  the  form  of  the  septum  primum  provision  for 
its  valvular  function.  The  funnel,  on  account  of  its  length,  can  be  applied  as  a  whole  to  the 
wall  of  the  left  atrium,  ventral  to  the  region  of  the  interatrial  septum,  and  being  here  com- 
pressed against  the  wall  and  its  lumen  obliterated,  may  in  this  way  prevent  regurgitation  from 
the  left  atrium  to  the  right.  Secondarily  this  position  is  favored  and  in  part  at  least  rendered 
permanent  by  the  adhesions  between  the  base  of  the  funnel  and  this  region  of  the  atrial  wall. 
There  is  of  course  a  possibility  that  a  circular  arrangement  of  the  muscle  of  the  valve  may 
by  a  sphinter  action  assist  its  function. 

In  other  respects  the  heart  conforms  to  the  usual  conditions  and  presents  little  that  requires 
comment.  The  left  atrium  receives  two  pulmonary  veins  from  the  right  lung,  three  from  the 
left,  the  small  additional  vessel  opening  between  the  other  two.  The  atrioventricular  valves 
have  the  usual  arrangement.  As  Turner  has  pointed  out  the  papillary  muscles  are  numerous, 
and  are  not  very  clearly  separated  into  groups.  In  the  right  ventricle  there  is  a  large  moderator 
band.  The  conus  arteriosus  is  capacious  in  contrast  to  the  rather  narrow  aortic  vestibule. 
The  same  disparity  obtains  between  the  arch  of  the  aorta  and  the  pulmonary  artery,  the  latter 
having  a  wide  circular  lumen,  while  that  of  the  former  is  reduced  to  a  narrow  slit.  The  inter- 
ventricular  foramen  is  closed. 

Thymus. —  The  two  lobes  of  the  thymus  rest  upon  the  pericardium  and  the  arch  of  the 
aorta  immediately  caudad  of  the  left  brachiocephalic  vein.  They  are  subequal,  disk-like,  the 
right  nearly  circular,  the  left  oval  with  its  long  axis  transverse.  Their  ventral  surfaces  are 

1  Rose,  C.     Beitrage  zur  vergleichenden  Anatomie  des  Hertzens  der  Wirbelthiere.     Morph.  Jahrb.,  Bd.  XVI,  1890. 


444  SC'Hl'LTK,  SEI  \VHALK. 

convex  and  distinctly  tabulated,  the  dorsal  nearly  flat.  Between  them  is  a  large  thymic  vein 
which  opens  into  the  left  brachiocephalic.  The  right  measures  transversely  7  mm.,  sagittally 
6  mm.,  and  has  a  thickness  of  4  mm. ;  for  the  left  body  these  dimensions  are  respectively  8  mm., 
6  mm.,  and  3  mm. 

Thyroid. —  The  Thyroid  has  the  form  of  a  TJ;  the  isthmus  is  constricted  and  the  lateral 
lobes  retort-shaped  with  their  broad  extremities  rostrad.  The  gland  is  in  contact  with  the 
fundus  of  the  tracheal  sac,  but  has  an  asymmetrical  position,  the  right  lobe  nearly  sagittal,  the 
left  with  a  distinct  inclination  laterad,  to  such  a  degree  indeed  that  it  is  wholly  concealed  by 
the  left  brachiocephalic  vein,  while  the  right  appears  in  ventral  view  between  the  right  vein  and 
the  tracheal  sac.  The  right  lobe  measures  13  mm.  in  length;  its  greatest  breadth  is  5  mm., 
and  greatest  thickness  3  mm.  The  corresponding  dimensions  of  the  left  are  7  mm.,  5  mm.,  and 
4  mm.  It  is  thus  not  only  asymmetrical,  but  the  left  lobe  is  also  smaller.  Near  its  rostral  pole 
on  the  left  is  a  small  oval  body  about  3  mm.  by  2  mm.,  of  glandular  appearance,  possibly  one 
of  the  parathyroids.  The  isthmus  measures  4  mm.  transversely,  by  2  mm.,  sagittally. 


ABDOMEN. 
(Plates  LI-LI  1 1.) 

The  abdominal  cavity  is  broad,  deep  and  capacious  in  its  rostral  portion;  caudad  it  is  a 
narrow  space  of  triangular  cross-section  bounded  on  its  dorso-lateral  sides  by  the  great  hypaxial 
muscles  and  ventrally  by  the  bladder,  urachus  and  accompanying  hypogastric  arteries.  The 
conformation  of  the  parts  is  such  that  the  plane  of  the  umbilicus  affords  a  natural  and  convenient 
division  between  these  regions.  The  caudal  margin  of  the  umbilicus  is  approximately  in  the 
same  transverse  plane  as  the  tip  of  the  last  rib,  in  this  specimen  the  thirteenth,  and  this  rib 
by  its  extremity  is  in  relation  with  the  first  third  of  the  kidney.  The  large  rostral  region  of  the 
abdomen  is  thus  at  the  sides  wholly  under  cover  of  the  ribs,  its  ventral  closure  being  given  by  the 
massive  recti.  The  attachment  of  the  diaphragm  in  the  ventral  midline  is  at  the  level  of  the 
extremities  of  the  sixth  ribs,  the  highest  point  of  the  dome  —  the  caval  aperture  —  lies  in  the 
fourth  space  vertically  above  the  extremity  of  the  fourth  rib.  The  caval  aperture  is  situated 
in  a  transverse  groove,  which  marks  the  abdominal  surface  of  the  diaphragm,  dividing  it  into 
a  ventral  slope  corresponding  to  the  pericardium  and  a  dorsal  slope,  which  on  its  thoracic  aspect 
corresponds  to  the  diaphragmatic  surfaces  of  the  lungs  and  costophrenic  sinus.  The  even  slope 
of  this  dorsal  or  caudal  plane  of  the  diaphragm  is  marked  on  each  side  by  a  shallow  fossa;  that 
on  the  right  is  the  result  in  the  hardened  specimen  of  moulding  upon  the  right  lobe  of  the  liver; 
that  on  the  left  upon  the  first  compartment  of  the  stomach.  In  addition  to  the  viscera  named, 
the  cephalic  compartment  of  the  abdomen  contains  the  spleen  and  pancreas,  the  duodenum, 
the  colic  loop  and  practically  the  whole  of  the  jejuno-ileum,  only  a  very  few  of  its  most  caudal 
coils  lying  caudad  of  the  plane  connecting  the  umbilicus  with  the  last  rib.  Against  its  dorsal 
wall,  retroperitoneally,  are  placed  the  adrenals,  the  suprarenal  segment  of  the  postcava  and  the 
upper  poles  of  the  kidneys.  The  liver  predominates  upon  the  right,  approximately  three  fifths 
of  its  bulk  lying  to  the  right  of  the  midplane,  caudally  overlying  the  right  kidney  for  nearly  half 
the  length  of  the  latter  organ.  To  it  caudally  are  closely  applied  the  pancreas,  the  ampulla 
duodeni,  and  the  stomach,  the  gastro- hepatic  omentum  being  reduced  to  little  more  than  reflec- 


PLATE  LI. 


PLATE  LI. 


Baleenoptera  borealis. 

Fig.  1 .     Ventral  view  of  genito-urinary  apparatus  in  situ.     2  X  natural  size. 
Fig.  2.    Jejuno-ileum,  ventral  view.     2  X  natural  size. 

Fig.  3.     Jejuno-ileum,  dorsal  view.     In  these  two  figures  the  major  coils  which  pass  from  left  to  right  are  tinted, 
those  passing  from  right  to  left  are  uncolored. 


1.  Adrenal. 

2.  Kidney. 

3.  Ovary. 

4.  Oviduct. 

5.  Ostium  abdominale. 

6.  Cornua  of  uterus. 

7.  Bladder. 

8.  Colon. 

9.  Postcava. 

10.  Left  adrenal  vein. 

11.  Coeliac  axis. 

12.  Superior  mesenteric  artery. 


13  Umbilical  artery. 

14.  Ligamentum  latum. 

15.  Ligamentum  teres. 

16.  Fold  on  venter  of  lig.  latum. 

17.  Plica  diaphragmatica  ovarii. 

18.  Mesentery. 

19.  Reflection  of  peritoneum  upon  visceral  complex. 

20.  Left  coronary  ligament. 

21.  (Esophagus. 

22.  Proximal  jejunum. 

23.  Terminal  ileum. 

24.  Centrum  tendineum. 


Memoirs  Am.  Mus.  Nat.  Hist. 


X.  S.,  Vol.  I,  Plate  LI. 


Fig.  1. 


Fig.  2. 


Fig.  3. 


BAL^ENOPTERA  BOREALIS. 


S(  III  1/1'K,  SKI  WHALE.  445 

tions  of  peritoneum.  Thus  there  is  left  for  the  closely  packed  coils  of  the  small  intestine  an 
oblong  space  extending  from  the  diaphragm,  rostrad  and  on  the  left,  to  the  median  surface 
of  the  right  kidney,  caudad  and  ventrad.  The  loop  of  the  duodenum  is  anchored  to  the  pos- 
terior parietes  as  is  also  the  arch  of  the  colon  which  loses  its  mesentery  above  the  level  of  the 
transverse  portion  of  the  duodenum. 

The  postumbilical  division  of  the  abdomen  is  very  narrow.  It  is  contracted  at  its  com- 
mencement by  the  projecting  kidneys  and,  ventrally,  by  the  large  mass  of  the  urachus  and 
hypogastric  arteries.  Into  the  pyramidal  interval  between  these  project  a  few  coils  of  the 
sn:all  intestine.  Caudad  of  the  kidneys  the  broad  ligament  divides  the  space  into  a  dorsal 
compartment  containing  the  colon  and  a  ventral  one  containing  the  bladder.  The  ventral 
compartment  is  limited  caudad  by  the  reflection  of  the  peritoneum  from  the  neck  of  the  bladder 
to  the  uterus.  The  dorsal  compartment  is  prolonged  as  a  narrow  recess  between  the  rectum 
and  vagina,  and  eventually  is  brought  to  an  end  close  to  the  perineum. 

(Esophagus. —  The  intra-abdominal  segment  of  the  oesophagus  has  a  very  considerable 
length,  measuring  from  the  diaphragm  to  its  cardiac  orifice  10  mm.  It  descends  with  a  slight 
sinistral  inclination  on  the  dorsal  aspect  of  the  first  gastric  compartment,  in  reference  to  which 
it  is  placed  also  somewhat  to  the  right,  as  Jungklaus 1  has  pointed  out.  On  the  left  it  is  defined 
by  a  shallow  furrow,  while  to  the  right  and  ventrally  it  is  separated  from  the  stomach  by  a  deep 
incisure,  which  in  the  natural  condition  of  the  parts  is  filled  with  rather  firm  connective  tissue. 
Caudad  its  relief  gradually  merges  in  that  of  the  first  compartment.  The  conformation  of  the 
cardiac  orifice  corresponds  with  the  external  character  of  this  junction.  Above  and  on  the 
right  it  is  marked  by  an  arched  ridge,  which  diminishes  to  the  left,  while  below,  its  dorsal  wall 
is  continued  into  that  of  the  stomach  without  demarcation.  The  lumen  is  marked  by  low 
longitudinal  ridges;  immediately  below  the  diaphragm  it  is  open,  having  a  transverse  diameter 
of  2  mm.,  but  distad  as  it  becomes  applied  to  the  stomach,  its  walls  are  in  contact.  The  walls 
here  are  about  1  mm.  in  thickness  and  the  tube  as  a  whole  is  slightly  flattened  dorso- vent  rally. 

Stomach. —  Four  compartments  are  present  exclusive  of  the  duodenal  ampulla,  which  is 
clearly  marked  off  from  the  stomach  by  a  sulcus  ectally  and  by  the  flaring  funnel  of  the  pylorus 
within.  This  enumeration  agrees  with  that  of  Pilliet  and  Boulart,2  and  with  the  more  recent 
results  of  Jungklaus,  who  to  a  careful  resume  of  the  literature  has  added  his  own  observations, 
based  so  far  as  Balcenoptera  is  concerned,  upon  three  foetuses  of  B.  musculus,  the  youngest 
measuring  63  cm.  While  conforming  in  the  main  to  Jungklaus'  description,  this  foetus  shows 
marked  differences  in  the  conformation  of  the  third  compartment.  The  minor  peculiarities  in 
the  shape  and  proportions  of  the  other  divisions  are  probably  referable  to  the  smaller  size, 
possibly  also  to  the  species  of  this  foetus.  The  whole  organ  is  admirably  preserved. 

The  first  compartment  is  too  little  expanded  to  deserve  Hunter's  appellation  of  egg-shaped. 
It  is  widest  at  its  middle,  thence  diminishing  towards  both  extremities.  The  fundus  is  bluntly 
rounded,  almost  truncated  in  external  view.  Here  both  muscularis  and  mucosa  are  thickest; 
then  become  thinner  towards  the  apex  of  the  stomach,  which  does  not  correspond  accurately 
with  the  junction  of  the  first  and  second  compartments,  but  is  formed  by  the  second  alone  as 
in  older  fretuses  (Jungklaus).  The  long  axis  is  directed  caudad,  to  the  left  and  somewhat  dorsad, 
so  that  the  fundus  rests  against  the  arch  of  the  colon,  and  the  right  margin  forms  almost  a  right 

_ — _ — _ 5 

1  Jungklaus.  F.     Der  Magen  der  Cetaceen.     Jena.  Zeitsch.  f.  Naturwiss.,  Bd.  32,  1898,  p.  1. 

-  Pilliet  ct  Houlsirt.     I/estonmr  des  Cetaces.     Jour,  de  1'Anat.  et  de  la  Physiol.,  An.  XXXI,  1895. 


446  SCHULTE,  SEI  WHALE. 

angle  with  the  greater  curvature  of  the  second  compartment.  From  this  angle  a  shallow  furrow 
ascends  upon  the  venter  of  the  stomach  towards  the  apex  to  the  level  of  the  communication 
between  the  first  two  compartments.  A  rather  deep  cleft  is  present  dorsally  in  a  correspond- 
ing position;  it  is  filled  with  areolar  tissue  and  in  it  the  gastric  artery  breaks  up  into  its  large 
branches.  Except  for  the  actual  region  of  communication,  therefore,  the  first  and  second  com- 
partments are  well  demarcated  ectally.  Entally  the  orifice  of  the  oesophagus  is  placed  at  the 
junction  of  the  upper  and  middle  thirds.  And  here  the  folds  of  the  dorsal  wall  are  continued 
into  the  oesophagus.  At  the  sides,  however,  there  is  no  radiation  from  the  orifice,  the  longi- 
tudinal folds  passing  it  on  the  left  with  no  disturbance  of  their  pattern.  This  holds  true  of  the 
right  side  also  in  general,  but  here  a  prominent  ridge  arches  round  the  opening,  and  this  is  crossed 
by  several  shallow  sulci  which  converge  towards  the  ossophagus.  They  are  confined  to  this 
single  ridge  and  produce  no  alteration  in  the  other  folds.  The  folds  are  somewhat  tortuous,  and 
as  the  intervening  sulci  are  narrow  and  deep,  there  is  a  distinct  interlocking  on  the  part  of  adja- 
cent folds,  which  lends  them  the  "  cerebriform "  appearance  noted  by  Carte  and  MacAlister. 
Under  the  binocular  this  surface  has  the  same  texture  as  that  of  the  oesophagus.  The  greatest 
length  of  this  compartment  from  apex  to  fundus  measures  21  mm.;  its  greatest  breadth  6.5  mm. 

The  junction  of  the  first  and  second  stomachs  is  marked  by  an  abrupt  change  in  the  mucous 
membrane,  which  has  a  softer,  more  succulent  appearance  in  the  second  stomach.  The  char- 
acter of  the  ridges  changes  also;  ventrally  the  ridges  of  the  first  compartment  simply  subside, 
dorsally  they  become  tortuous  and  irregular,  in  marked  contrast  to  the  even  longitudinal  folds  of 
the  second  compartment.  The  line  of  junction  is  directed  from  the  summit  of  the  doubled  wall, 
where  the  two  compartments  are  in  apposition,  to  the  left  and  rostrad,  passing  very  slightly  to 
the  left  of  the  apex  of  the  stomach.  The  orifice  of  communication  has  a  nearly  horizontal  lower 
lip  formed  by  the  summit  of  the  wall  just  mentioned;  the  remainder  of  its  contour  is  arched. 
Vertically  it  measures  3  mm.,  transversely  about  4  mm. 

The  second  compartment  is  larger  than  the  first  and  diverges  from  it  to  the  right.  It 
measures  24  mm.  hi  a  straight  line  from  the  apex  to  the  orifice  of  the  third  stomach,  13  mm.  in 
its  region  of  greatest  breadth.  Its  general  shape  is  fusiform.  The  greater  curvature  is  evenly 
convex;  the  lesser,  at  first  strongly  convex  to  the  right,  becomes  concave  distad  and  assumes 
a  horizontal  direction  as  the  third  stomach  is  approached.  The  walls  are  gently  convex  except 
where  applied  to  the  first  stomach.  Here,  immediately  below  the  proximal  orifice,  there  is  a 
slight  bulging  inwards  of  the  left  wall.  The  mucous  membrane  on  the  dorsal  wall  is  thrown 
into  several  longitudinal  folds,  in  some  places  connected  by  lower  transverse  ridges.  The  folds 
are  best  marked  along  the  lesser  curvature.  A  portion  of  the  wall  is  smooth.  The  ventral 
wall,  on  the  other  hand,  is  marked  by  transverse,  forking  folds,  which  radiate  from  the  base  of 
the  double  wall  which  separates  this  compartment  from  the  first.  Farther  distad  are  four 
or  five  oblique  rugae,  running  from  the  greater  to  the  lesser  curvature  and  converging  towards  the 
third  stomach.  Evidently  in  this  compartment  the  primitive  longitudinal  folds  are  in  process 
of  being  replaced  by  the  transverse  ones  of  the  older  foetus  (Jungklaus)  and  adult  (Perrin).  The 
surface  of  the  mucosa  is  more  delicate  than  that  of  the  first  compartment  and  appears  finely 
granular;  under  the  binocular  this  appearance  is  found  to  be  due  to  the  presence  of  small  arese 
gastric^  separated  by  shallow  sulci. 

The  lower  part  of  the  second  compartment  adjacent  to  the  greater  curvature  and  leading 
to  the  orifice  of  the  third  requires  a  more  particular  description.  It  is  partially  set  off  from  the 


SCHULTE,  SEI  WHALE.  447 

remainder  of  the  second  stomach  by  an  obliquely  longitudinal  ridge,  which  beginning  near  the 
middle  of  the  greater  curvature  extends  distad  across  the  dorsal  wall  and  reaching  the  lesser 
curvature  changes  direction,  becomes  transverse,  and  passes  to  the  ventral  wall.  Here  about 
midway  between  the  curvatures  it  declines  abruptly  running  out  into  small  ridges  which  diverge 
towards  the  greater  curvature.  Beneath  the  arch  of  its  transverse  segment  is  left  a  small  orifice 
of  dorso-caudal  position  —  that  is  in  the  region  of  the  dorsal  paries  and  greater  curvature  - 
which  leads  into  the  third  compartment.  A  furrow  on  the  ectal  surface  is  associated  with  the 
proximal  obliquely  longitudinal  segment  of  this  ridge.  It  is  very  shallow  and  not  of  such  a 
character  as  to  suggest  that  the  ridge  may  be  the  result  of  post  mortem  compression  or  shrink- 
age. A  fold  of  that  kind  is  present  on  the  ventral  wall  of  this  compartment;  it  is  easily  obliter- 
ated by  manipulation  and  has  no  resemblance  to  the  formation  we  are  considering,  which  is 
of  solid  massive  structure.  The  portion  of  the  second  stomach  distal  to  this  ridge  is  marked 
by  transverse  folds  of  the  mucosa  and  although  it  produces  little  external  protrusion,  evidently 
corresponds  to  Jungldaus's  description  of  "einer  relativ  tiefen,  ventralen,  rinnenartigen  Aus- 
buchtung  auf  der  linken  Seite;  dieselbe  fuhrt  direkt  auf  das  Orificium  des  dritten  Magens. "  J 

The  third  compartment,  defined  against  the  second  on  the  ectal  surface  by  the  slight 
furrow  already  mentioned,  is  distally  without  surface  demarcation  from  the  fourth  stomach. 
Entally  its  boundary  here  is  given  by  a  ridge  on  the  rostro-ventral  wall,  which  displaces  the 
orifice  of  communication  to  the  region  of  the  greater  curvature  dorsally.  Thus  both  entrance 
and  exit  are  adjacent  to  the  greater  curvature  and  of  dorsal  position.  A  third  fold  of  inter- 
mediate size  and  corresponding  to  an  ectal  sulcus  and  angulation  of  the  tube  is  placed  between 
the  other  two.  This  springs  from  the  dorsal  wall  and  greater  curvature  leaving  but  a  small 
communication  close  to  the  lesser  curvature  vehtrally,  to  maintain  the  lumen  of  the  compart- 
ment, which  thus  is  rendered  canal-like  and  of  the  shape  of  inverted  U,  for  the  intermediate  fold 
is  broad  as  well  as  high  and  appropriates  a  large  part  of  the  space  between  the  other  two  folds. 
The  mucous  surface  is  smooth  and  shows  no  trace  of  other  folds.  The  diameter  nowhere  exceeds 
2.5  mm.,  the  orifices  are  distinctly  less.  Its  length  is  6  mm.,  its  diameter  externally  is  5.5  mm. 

In  older  foetuses  of  B.  musculus  Jungklaus  describes  a  third  compartment  of  radically 
different  conformation.  It  was  dilated,  of  thinner  walls  than  the  others,  and  defined  by  two 
changes  of  direction  in  the  axis  of  the  stomach,  with  resulting  angulation  and  the  formation  of 
double  separating  walls  at  both  its  distal  and  proximal  extremities.  The  two  angulations  of 
the  distal  portion  of  the  stomach  in  this  foetus  are  incident,  one  at  the  middle  fold  of  the  third 
compartment,  one  in  the  terminal  portion  of  the  fourth  stomach.  It  is  difficult  therefore  to 
see  in  this  stomach  a  stage  antecedent  to  those  of  Jungklaus,  for  the  supposition  that  such 
angulation  can  be  effaced  and  new  ones  form  has  no  observations  to  support  it.  This  raises 
the  question  of  divergence  between  the  species  of  the  genus  in  this  character,  a  possibility  which 
is  in  a  measure  suggested  by  the  wide  discrepancies  in  the  literature  of  the  third  compartment 
in  the  adult. 

The  fourth  compartment  presents  a  change  of  direction  in  its  course.  In  its  proximal  and 
longer  portion  its  axis  runs  caudad,  dorsad  and  to  the  right,  in  its  short  distal  segment,  rostrad, 
dorsad  and  very  slightly  to  the  left.  This  change  is  effected  by  a  gradual  curve  on  the  greater 
curvature,  but  on  the  lesser  is  accompanied  by  a  sharp  angulation,  immediately  beyond  which, 

1  Jungklaus,  F.,  op.  cit.,  p.  49. 


44S  SCHl'LTE,  SEI  WHALE. 

indeed  upon  its  distal  slope,  is  situated  the  flaring  pylorus.  This  projects  strongly  into  the 
duodenum.  The  fourth  compartment  is  thicker  walled  than  the  stomach  elsewhere  save  at  the 
fundus  of  the  first.  Its  lumen  diminishes  rapidly  towards  the  pylorus.  In  its  widest  portion 
it  is  smooth  internally,  but  as  it  contracts  it  becomes  marked  with  slight  longitudinal  ridges 
and  sulci  which  are  prolonged  upon  the  projecting  pylorus  to  its  edge.  In  length  this  compart- 
ment measures  8  mm.,  in  maximum  diameter  6  mm.  Its  greatest  lumen  is  3  mm.  which  dimin- 
ishes to  less  than  1  mm.  just  before  the  pylorus  is  reached. 

Duodenum. —  Four  portions  may  be  distinguished,  the  ampulla,  descending,  transverse, 
and  ascending  duodenum.  The  ampulla  is  a  pyriform  dilatation,  attaining  its  maximum  diam- 
eter a  little  distad  of  the  pyloric  sulcus  and  more  gradually  diminishing  subsides  to  the  dimen- 
sions of  the  rest  of  the  duodenum  at  the  sharp  angle  where  it  joins  the  descending  portion.  Its 
axis  is  directed  dorsad,  rostrad,  and  slightly  to  the  left,  continuing  the  direction  of  the  terminal 
portion  of  the  fourth  gastric  compartment.  It  has  a  length  of  7  mm.,  a  maximum  lumen  of 
2.5  mm.,  which  at  its  junction  with  the  descending  duodenum  is  reduced  to  1  mm.  Its  walls  are 
thickest  at  the  pylorus  and  diminished  in  strength  distad.  The  mucous  surface  shows  no  folds 
but  is  beset  with  numerous  conical  to  finger-shaped  villi.  The  ampulla  rostrad  and  on  the  left  is 
in  relation  with  the  horizontal  portion  of  the  pancreas  and  is  crossed  dorsad  and  to  the  right 
of  this  by  the  portal  vein  and  hepatic  artery  on  their  way  to  the  liver.  On  the  right  it  is  free 
and  covered  by  peritoneum,  while  caudad  it  is  in  peritoneal  contact  with  the  descending  duo- 
denum. 

The  remainder  of  the  duodenum  describes  a  typical  loop  about  the  root  of  the  mesentery. 
It  is  U-shaped  with  a  tendency  to  angulation  at  the  junction  of  its  descending  and  transverse 
portions.  The  loop  is  occupied  by  the  vertical  portion  of  the  pancreas,  leaving  a  broad  longi- 
tudinal space  to  the  left  for  the  large  superior  mesenteric  artery  and  vein.  The  whole  descend- 
ing duodenum  and  the  transverse,  as  far  as  these  vessels,  are  free  and  covered  by  peritoneum 
dorsally,  so  that  only  the  curved  termination  of  the  transverse  and  the  ascending  portion  have 
become  adherent  to  the  parietes.  The  degree  of  anchorage  of  the  duodenum  is  thus  seen  to  be 
small  and  limited  to  the  portions  to  the  left  of  the  median  line.  The  descending  duodenum  runs 
caudad,  distinctly  ventrad  and  slightly  to  the  right,  being  closely  applied  to  the  ampulla  and 
pyloric  extremity  of  the  stomach,  to  which  however  no  adhesions  have  been  contracted.  The 
transverse  duodenum  passes  behind  the  ascending  colon,  from  which  and  from  the  colic  portion 
of  the  mesenterium  commune  it  is  free,  the  root  of  the  mesentery  persisting  in  its  primitive 
condition  and  not  being  extended  by  secondary  adhesions  caudad  and  to  the  right,  in  the  direc- 
tion of  the  iliac  fossa.  This  is  the  explanation  I  believe  of  Hunter's  :  statement:  "in  this  course 
behind  the  mesentery  it  is  exposed,  as  in  most  quadrupeds  not  being  covered  by  it,  as  in  the 
human,"  which  Weber  finds  difficult  to  understand.  The  ascending  duodenum  passes  cephalad 
and  to  the  left,  between  the  root  of  the  mesentery  and  the  descending  colon,  to  both  of  which 
it  is  adherent  though  to  the  colon  only  close  to  the  duodeno-jejunal  angle.  This  flexure  is  placed 
immediately  below  the  arch  of  the  colon,  the  intestine  here  turning  ventrad  and  to  the  right 
at  a  sharp  angle.  Thus  the  loop  of  the  duodenum  with  the  included  portion  of  the  pancreas 
and  the  root  of  the  mesentery  form  a  disk,  to  the  front  and  left  border  of  which  the  colon  has 
been  applied,  and  which  has  contracted  secondary  adhesions  dorsally  to  the  parietes  only  along 


Hunter,  John.     Observations  on  the  structure  and  economy  of  whales.     Philos.  Trans.,  1787. 


SCHfLTE,  SKI  WHALE.  449 

the  lines  of  the  postcava  on  the  right  and  the  ascending  duodenum  and  angle  of  the  colic  arch 
on  the  left  of  the  primitive  mesenteric  root.  As  a  result  the  descending  duodenum,  more  than 
half  of  the  transverse,  and  a  considerable  area  of  the  pancreas  are  free  on  the  right  of  the  post- 
cava, while  the  ascending  colon  covers  and  is  adherent  to  the  vertical  portion  of  the  pancreas, 
ventrally  concealing  it  from  view.  On  the  other  hand  the  duodenum  is  wholly  excluded  from 
the  lesser  sac,  the  usual  peritoneal  surface  on  the  left  of  its  first  portion,  here  ampulla,  is  occu- 
pied by  the  horizontal  portion  of  the  pancreas,  which  from  its  high  position  and  adherence  to 
the  liver  must  be  considered  to  have  invaded  the  gastro-hepatic  omentum  near  its  primitively 
free  margin,  following  the  line  of  the  bile  duct  and  portal  vein  ventrally,  in  the  position  occasion- 
ally taken  by  the  development,  as  a  variant,  of  the  left  ventral  pancreatic  anlage.  The  peri- 
toneal covering  of  this  region  is  still  further  reduced  by  the  obliteration  of  the  foramen  of  Winslow 
(vide  infra  p.  452). 

In  its  interior  the  duodenum  is  smooth  save  for  the  presence  of  finger-shaped  and  conical 
villi.  I  did  not  lay  it  open  in  its  full  length,  but  only  to  the  beginning  of  its  transverse  portion. 
In  this  portion  there  were  no  valvulse  conniventes  and  the  only  definite  longitudinal  ridge  was 
related  to  the  intramural  portion  of  the  bile  duct.  This  elevation  began  at  the  angle  between 
the  ampulla  and  the  second  portion  and  continued  through  about  half  the  length  of  the  descend- 
ing duodenum.  At  its  distal  extremity  was  a  small  punctate  orifice.  The  several  portions 
of  the  duodenum  had  the  following  lengths  irrespective  of  their  curvature:  ampulla  7  mm.; 
descending  11  mm.;  transverse  10  mm.;  ascending  14  mm. 

Jejuno-ileum. —  The  remainder  of  the  small  intestine  forms  a  closely  coiled  mass  which 
occupies  an  oblique  position  in   the  abdomen,  extending  from  the  first  compartment  of  the 
stomach  and  the  diaphragm  on  the  left,  caudad  and  dextrad  to  the  interval  between  the  extrem- 
ity of  the  liver  and  the  right  kidney.     The  intestine  is  all  but  wholly  confined  to  the  preum- 
bilical  portion  of  the  abdomen,  only  a  few  small  coils  project  beyond  the  umbilicus  into  the 
space  between  the  kidneys.     The  mesentery  has  a  short  attachment  to  the  right  of  the  ascending 
duodenum  occupying  the  interval  between  it  and  the  ascending  limb  of  the  colon  loop.     At  the 
cephalic  margin  of  the  transverse  duodenum  the  colon  becomes  free  and  here  the  mesentery  is 
continuous  with  the  mesocolon.     As  the  ileo-colic  junction  is  just  caudad  of  the  duodenum,  the 
extent  of  free  mesocolon  at  this  point  is  but  small,  yet  to  this  degree  the  mesenterium  com- 
mune has  been  retained.     The  coils  of  the  small  intestine  are  closely  packed  and  very  numerous. 
They  may  be  described  in  Gadow's  terms  as  plagiocoelous  with  a  very  considerable  degree  of  tel- 
ogyry.     While  perhaps  the  majority  of  the  coils  showed  a  tendency  to  form  a  double  spiral, 
in  few  did  it  much  exceed  a  half  turn  and  in  none  was  a  complete  turn  accomplished.     On  the 
other  hand  some  of  the  coils  were  quite  irregular.     On  further  analysis  the  mass  of  small  coils 
can  be  resolved  into  six  major  loops,  each  of  which  crosses  the  line  of  the  mesentery  transversely, 
from  right  to  left  or  vice  versa  and  having  done  so  turns  caudad  to  be  continuous  with  the  suc- 
ceeding loop,  which  returns  to  the  opposite  side  reversing  the  general  direction  of  its  predecessor. 
The  first  of  these  is  directed  from  left  to  right,  and  its  mass  of  coils  of  moderate  size,  is  accumu- 
lated at  the  cephalic  extremity  of  the  mesentery.     The  second  loop  reverses  this  general  direc- 
tion, and  so  on,  the  odd  numbered  loops  being  directed  from  left  to  right,  the  even  from  right 
to  left.     The  third  and  fifth  are  large,  the  intervening  fourth  is  very  short,  while  the  sixth  arch- 
ing round  the  caudal  extremity  of  the  mesentery  far  exceeds  any  of  the  others  in  extent.     At  the 
ileo-colic  junction  the  terminal  ileum  passes  cephalad  and  somewhat  ventrad  and  to  the  right, 


450  SCHULTE,  SEI  ^YHALE. 

being  closely  applied  to  the  ccecum.  The  change  of  diameter  in  the  jejuno-ileum  is  not  great, 
and  in  many  places  the  coils  were  so  appressed  as  to  be  flattened  or  otherwise  deformed  in 
contour.  As  a  whole,  however,  the  diameter  diminishes  distad  and  it  can  be  said  of  the  first 
three  loops  that  they  perceptibly  exceed  the  last  three  in  size  of  the  tube.  There  was  no  trace 
of  Meckel's  diverticulum. 

Colon. —  From  the  ileo-colic  junction,  which  faces  to  the  left,  the  colon  passes  rostrad  and 
to  the  left  towards  the  spleen,  where  it  turns  sharply  upon  itself  describing  a  narrow  arch  rostrad 
of  the  duodeno-jejunal  junction  and  descends  to  the  left  of  the  ascending  portion  of  the  duo- 
denum. It  reaches  the  midline  in  the  interval  between  the  kidneys  and  following  the  contour  of 
the  left  kidney  makes  a  decided  excursion  to  the  left  at  its  lower  pole.  Thereafter  it  gradually 
returns  to  the  midline,  which  it  regains  opposite  the  upper  third  of  the  vagina,  there  con- 
tinuing to  its  termination  in  the  rectum.  The  mesocolon  is  narrow  in  its  whole  extent,  attain- 
ing a  maximum  breadth  of  5  mm.  only  for  a  short  distance  at  the  lower  pole  of  the  left  kidney. 
From  the  cephalic  border  of  the  transverse  duodenum  rostrad  to  a  little  beyond  the  summit 
of  the  loop,  that  is,  precisely,  to  a  point  vertically  above  the  left  margin  of  the  ascending  duo- 
denum, the  colon  has  lost  its  mesentery.  Thence  caudad  as  far  as  the  transverse  portion  of 
the  duodenum,  the  right  leaf  of  the  mesocolon  is  fused  with  the  primitive  mesentery  of  the 
duodenum,  while  its  left  leaf  has  become  adherent  to  the  parietes,  and  is  reflected  directly  from 
the  colon  to  the  dorsal  abdominal  wall.  These  two  segments  of  the  intestine,  ascending  duo- 
denum and  descending  colon  are  in  contact,  but  retain  their  peritoneal  covering,  and  are  not 
otherwise  attached  to  one  another  than  by  the  fusion  of  their  mesenteries  in  the  manner  just 
described.  The  arch  of  the  colon  is  in  contact  on  the  left  with  the  spleen  and  the  tail  of  the 
pancreas  which  separate  it  from  the  first  portion  of  the  stomach.  To  the  right  it  continues 
to  have  the  pancreas  adherent  to  its  rostral  aspect  and  is  further  overlain  by  the  papillary  process 
of  the  liver,  from  which  it  is  separated  by  the  lesser  sac. 

The  obliquely  ascending  colon  is  fused  with  the  lobe  of  the  pancreas  that  occupies  the 
duodenal  loop.  From  the  rostral  margin  of  the  transverse  duodenum,  as  has  been  said,  it  is 
free  and  retains  its  portion  of  the  mesenterium  commune.  The  interval  between  the  ascend- 
ing and  descending  loops  of  the  colon  is  small  and  is  occupied  by  the  root  of  the  mesentery,  the 
ascending  portion  of  the  duodenum,  and  the  duodeno-jejunal  junction.  The  ascending  colon 
has  a  length  of  23  mm. 

Caecum. —  The  ccecum  is  short,  about  4  mm.  in  length,  and  closely  applied  to  the  terminal 
ileum.  I  could  find  no  distinct  folds  between  them.  Ventrad  however  the  two  were  adherent 
for  a  short  distance,  which  may  be  taken  as  an  indication  of  the  anterior  vascular  fold.  The 
ccecum  is  rounded  at  its  apex  but  somewhat  beveled  at  the  expense  of  its  right  margin.  The 
ileum  joins  the  colon  almost  in  line  with  its  long  axis,  the  region  of  junction  lying  upon  the  right 
kidney  and  against  the  right  leaf  of  the  mesentery.  It  is  thus  placed  against  the  dorsal  wall 
of  the  abdominal  cavity  and  not  well  ventrad  as  is  sometimes  stated.  As  the  ileo-colic  junc- 
tion faces  to  the  left  it  is  evident  that  not  only  has  the  gut  as  a  whole  undergone  rotation,  but 
that  the  further  act  of  rotation  of  the  ascending  colon  on  its  long  axis  has  also  been  accom- 
plished. 

Liver. —  The  liver  is  of  large  size,  massive  and  of  relatively  simple  conformation.  It 
occupies  almost  the  whole  of  the  preumbilical  region  on  the  right  side,  extending  from  the  dia- 
phragm well  down  upon  the  kidney.  The  left  lobe  is  much  smaller  in  all  dimensions,  as  not 


SCHULTE,  SEI  WHALE.  451 

only  the  stomach  but  the  greater  part  of  the  intestine  is  contained  in  the  left  preumbilical 
region.  Save  for  some  damage  to  the  surface  of  the  left  lobe,  the  liver  is  well  preserved  and 
so  successfully  hardened  in  situ  that  it  retains  distinct  impressions  of  the  adjacent  viscera. 
The  surface  relief  therefore  merits  a  somewhat  detailed  description.  It  is  convenient  to  recog- 
nize a  ventral  and  a  dorsal  surface,  the  latter  divided  into  diaphragmatic  and  visceral  areas, 
which  are  further  distinguished  by  their  somewhat  different  orientation.  The  demarcation 
of  the  ventral  and  dorsal  surface  is  facilitated  by  the  coaptation  of  the  liver  to  the  diaphragm. 
This  it  will  be  remembered  presents  two  sloping  planes,  corresponding  to  the  caudal  surfaces 
of  the  lungs  and  that  of  the  pericardium,  the  two  meeting  in  a  transverse  groove,  in  the  right 
third  of  which  is  placed  the  aperture  of  the  postcava.  This  groove  expresses  itself  in  the  relief 
of  the  liver  as  a  distinct  transverse  ridge,  from  which  the  surface  falls  away  ventrad  and  dorsad, 
in  consequence  of  which  the  organ  in  right  profile  view  has  a  wedged  shaped  upper  contour. 
To  the  left  of  the  postcava  the  direction  of  the  transverse  ridge  is  continued  by  the  border  of 
the  left  lobe  that  gives  attachment  to  the  lateral  or  coronary  ligament.  Thus  upon  the  dia- 
phragmatic aspect  of  the  liver  there  is  given  a  natural  demarcation  of  ventral  and  dorsal  sur- 
faces. Caudad  the  boundary  is  given  by  the  sharp  margin  as  far  as  the  pointed  prolongation 
of  the  right  lobe  which  overlies  the  kidney.  Running  rostrad  from  this  point  a  well  marked 
ridge  at  the  right  margin  of  the  renal  impression  divides  the  ventral  from  the  dorsal  surface 
for  about  half  their  sagittal  extent.  Rostrad  of  this  the  boundary  is  somewhat  less  definite 
and  is  given  by  a  rounded  eminence  of  the  right  lobe,  which  fits  into  a  corresponding  concavity 
of  the  diaphragm  slightly  caudad  of  its  pulmonary  plane,  and  corresponding  to  the  sinus  pleurae 
on  the  thoracic  aspect  of  the  diaphragm.  Thus  the  boundary  between  the  ventral  and  the 
dorsal  surface  has  been  traced  round  the  periphery  of  the  liver  to  our  starting  point,  the  trans- 
verse ridge  on  its  diaphragmatic  aspect. 

The  sharp  ventral  or  caudal  margin  demands  a  word  of  description.  The  notch  for  the 
umbilical  veins  is  very  deep.  To  the  left  of  this  the  border  has  an  oblique  course,  crossing  the 
second  compartment  of  the  stomach,  leaving  exposed  its  greater  curvature  together  with  almost 
the  whole  of  the  first  compartment,  which  is  covered  only  by  the  large  left  coronary  ligament. 
To  the  right  of  the  umbilical  notch  the  liver  is  prolonged  caudad  beside  the  vein  for  about  a 
centimetre;  the  margin  then  turns  obliquely  to  the  right.  Here  the  caudal  extremity  is  formed 
by  an  angular  projection  which  rests  upon  the  right  kidney.  Thus  defined  the  ventral  surface 
is  strongly  convex  from  side  to  side,  being  moulded  upon  the  diaphragm  and  recti,  except  rostrad 
where  it  presents  a  flattened  triangular  impression  corresponding  to  the  base  of  the  pericar- 
dium. This  is  crossed  by  the  attachment  of  the  falciform  ligament,  with  reference  to  which 
it  is  asymmetrical  about  three  fifths  belonging  to  the  right  lobe.  Sagittally  the  remainder  of  the 
surface  is  nearly  straight,  only  in  the  region  of  the  renal  prolongation  on  the  right  it  slopes  slightly 
dorsad  in  consequence  of  the  contraction  of  the  abdomen  in  the  vicinity  of  the  umbilicus. 

The  dorsal  surface  on  the  left  is  deeply  grooved  for  the  reception  of  the  stomach.  At  the 
bottom  of  this  groove  is  situated  the  ductus  venosus  buried  in  the  substance  of  the  liver,  its 
fissure  being  marked  only  by  the  reflection  of  the  peritoneum.  The  Spigelian  lobe  is  of  large 
size  and  peculiar  in  the  great  development  of  its  processus  papillaris.  This  projects  strongly 
caudad  and  to  the  left,  covered  by  peritoneum  of  the  lesser  sac;  it  is  contact  with  the  stomach 
dorsad  to  the  left  and  ventrad,  and  with  the  upper  lobe  of  the  pancreas  and  the  arch  of  the 
colon  on  the  right,  the  latter  being  also  caudal.  On  its  dorsal  aspect  it  is  separated  from  the 


4,-)2  SCHULTE,  SEI  WHALE. 

remainder  of  the  Spigelian  lobe  by  a  deep  groove,  which  lodges  the  gastric  artery;  at  this 
point  the  reflection  of  the  peritoneum  of  the  lesser  sac  occurs,  so  that  there  is  no  proper  Spigc- 
lian  recess  and  the  surface  of  that  lobe  becomes  adherent  to  the  diaphragm.  On  the  right 
the  processus  papillaris  is  separated  by  a  deep  notch  from  the  small  depressed  caudate  lobe  and 
here  the  upper  lobe  of  the  pancreas  is  adherent.  On  the  right  the  Spigelian  lobe  is  bounded  by 
a  narrow  caval  fissure,  the  approximated  walls  of  which  conceal  the  postcava  deep  in  the  sub- 
stance of  the  liver.  The  dorsal  surface  of  the  right  lobe  is  marked  by  an  oblique  ridge,  beginning 
at  a  small  pyramidal  eminence  beside  the  postcava,  the  rudimentary  caval  lobe,  and  terminat- 
ing at  the  caudal  pointed  extremity  of  the  organ.  This  ridge  marks  the  right  limit  of  the  renal 
impression.  Rostrad  of  it  is  the  large  triangular  non-peritoneal  surface  and  above  this  the  emi- 
nence corresponding  to  the  sinus  pleurae  and  the  pulmonary  impression.  The  renal  impression 
is  very  large,  concave  and  obliquely  placed.  It  terminates  just  caudad  of  the  caval  eminence, 
which  is  non-peritoneal  and  adherent  to  the  adrenal.  Mesal  to  the  renal  impression,  near  the 
caudal  margin,  is  a  triangular  area  slightly  concave,  which  is  in  apposition  with  coils  of  the 
small  intestine.  Between  this  and  the  deeply  depressed  hilum,  the  liver  is  in  contact  with 
the  duodenum.  The  fissure  for  the  umbilical  veins  is  deep  and  broad.  The  two  umbilical  veins 
unite  about  a  centimeter  before  reaching  the  hilum.  The  portal  vein  enters  the  hilum  at 
the  extreme  right  rostral  angle,  having  the  hepatic  artery  on  the  left  and  the  bile  duct  on 
its  caudal  aspect.  In  the  hilum  it  enlarges,  as  Carte  and  MacAlister  also  found,  and  is  con- 
nected to  the  left  by  a  very  large  branch  with  the  common  umbilical  vein  and  the  beginning  of 
the  ductus  venosus.  Before  entering  the  liver  the  portal  vein,  lying  in  a  groove  between  the 
upper  and  the  duodenal  portions  of  the  pancreas,  and  directed  ventrad,  rostrad  and  to  the  right, 
is  closely  applied  and  adherent  to  the  left  side  and  venter  of  the  postcava.  In  this  way  the  fora- 
men of  Winslow  is  occluded,  and  the  separation  of  greater  and  lesser  sacs  is  further  increased 
by  the  adherence  of  the  superior  lobe  of  the  pancreas  to  the  caudate  lobe.  This  latter  condi- 
tion has  the  effect  of  replacing  the  right  or  transverse  portion  of  the  gastro-hepatic  omentum 
by  an  extensive  surface  of  contact  and  adhesion  in  the  region  of  the  pylorus,  and  of  substitut- 
ing for  the  usual  peritoneal  contact  of  these  organs,  a  firm  adhesion  to  the  visceral  surface  of 
the  liver. 

As  has  been  said,  the  Spigelian  lobe  is  adherent  to  the  diaphragm  as  far  caudad  as  the 
groove  of  the  gastric  artery.  In  two  regions,  therefore,  the  adhesion  of  the  liver  to  adjacent 
structures  has  been  increased  at  the  expense  of  the  lesser  sac.  Nor  was  I  able  to  convince  myself 
that  the  lesser  sac  extended  to  the  right  side  of  the  oesophagus,  but  here  owing  to  the  small  size 
of  the  object  and  the  friability  of  the  liver  at  this  point,  the  material  was  inadequate  to  permit 
a  definite  observation.  In  three  specimens  of  Tursiops  truncatus  from  the  New  York  Aqua- 
rium, with  very  different  conformation  of  the  organs  concerned,  essentially  the  same  conditions 
obtained  in  their  peritoneal  relations.  The  foramen  of  Winslow  was  obliterated;  there  was 
an  extensive  adhesion  between  liver  and  pancreas;  the  Spigelian  lobe  was  extensively  adherent 
to  the  diaphragm.  Between  its  ventral  extremity  and  the  oesophagus  however  was  a  small 
remnant  of  the  lesser  cavity,  but  this  was  wholly  cut  off  from  the  remainder  of  the  lesser  sac. 
It  is  apparent  therefore  that  in  both  groups  of  the  Cetacea  similar  processes  have  been  at  work 
to  modify  the  topography  of  the  upper  abdomen,  and  that  these  have  resulted  primarily  in  a 
closer  approximation  and  more  intricate  coaptation  of  the  several  viscera  to  one  another,  so  that 
they  have  been  welded  into  a  complex  with  increased  surfaces  of  adhesion,  both  to  one  another 
and  to  the  diaphragm. 


PLATE  LII. 


PLATE  LII. 


Balcenoptera  borealis. 

Fig.  1.  Ventral  view  of  stomach,  duodenum  and  arch  of  colon.     2  X  natural  size. 

Fig.  2.  Interior  of  stomach.     2  X  natural  size. 

Fig.  3.  Dorsal  view  of  preumbilical  visceral  complex.     2  X  natural  size. 

Fig.  4.  Dorsal  view  of  liver.     2  X  natural  size. 


1.  (Esophagus. 

2.  Stomach,  compartment  1. 

3.  Stomach,  compartment  2. 

4.  Stomach,  compartment  3. 

5.  Stomach,  compartment  4. 

6.  Duodenum,  descending. 

7.  Duodenum,  transverse. 

8.  Duodenum,  ascending. 

9.  Osecum. 

10.  Colon. 

11.  Ileum. 

12.  Attachment  of  great  omentum. 

13.  Root  of  the  mesentery. 

14.  Superior  mesenteric  artery. 

15.  Superior  mesenteric  vein. 

16.  Postcava. 


17.  Caval  fissure. 

18.  Portal  vein. 

19.  Hepatic  artery. 

20.  Gastric  artery. 

21.  Spleen. 

22.  Pancreas. 

23.  Diaphragmatic  surface  of  the  right  lobe  of  liver. 

24.  Spigelian  lobe. 

25.  Processus  papillaris. 

26.  Left  coronary  ligament. 

27.  Falciform  ligament. 

28.  Umbilical  veins. 

29.  Renal  impression. 

30.  Duodenal  area. 

31.  Intestinal  area.    . 

32.  Gastric  area. 


Memoirs  Am.  Mus.  Nat,  Hist. 


X.  P.,  Vol.  I,  Plate  LIT. 


Fig.  1. 


29 


Fig.  2. 


Fig.  4. 


BAL^NOPTERA  BOREALIS. 


SCHULTE,  SET  WHALE.  453 

A  major  role  in  determining  these  conditions  in  this  foetus  must  be  assigned  to  the  general 
shape  of  the  abdominal  cavity,  which  caudad  of  the  umbilicus  is  reduced  to  small  dimensions 
and  contains  only  the  genito-urinary  organs  and  the  terminal  colon.  In  consequence  the  whole, 
or  all  but  the  whole,  of  the  small  intestine  has  been  displaced  cephalad  of  the  usual  position  in 
mammals  and  there  has  resulted  a  very  compact  massing  together  of  the  remaining  viscera  below 
the  diaphragm.  In  the  foetuses  of  Tursiops  from  Mr.  Andrews's  collection,  the  post  umbilical 
compartment  was  of  larger  size  and  contained  a  large  part  of  the  jejuno-ilium,  while  the  enor- 
mous liver,  of  which  the  left  lobe  was  far  larger  than  in  the  Balcenoptera,  occupied  the  bulk  of  the 
space  in  the  rostral  compartment.  To  it  the  stomach,  pancreas  and  duodenum  were  closely 
adherent. 

Pancreas. —  This  organ  has  two  large  divisions  or  lobes  which  diverge  from  their  region 
of  union  beside  the  ampulla  duodeni;  one,  sagittal  in  position,  passes  caudad  into  the  loop  of 
the  duodenum,  the  other,  directed  obliquely  cephalad  and  to  the  left,  lies  upon  the  ascending 
colon  and  sends  a  prolongation  beyond  its  arch  upon  the  first  stomach  to  touch  the  spleen.  In 
dorsal  view  these  two  divisions  are  separated  by  a  deep  and  nearly  horizontal  groove  which  lodges 
the  portal  vein  and  hepatic  artery.  The  transverse  lobe  or  body  is  placed  immediately  above 
the  coeliac  axis,  which  dividing  into  hepatic  and  gastric  arteries,  marks  out  a  triangular  area 
on  the  pancreas,  that  may  be  taken  as  the  dorsal  surface  of  the  body.  This  is  non-peritoneal ; 
its  upper  margin  is  well  defined,  and  separates  it  from  the  hepatic  surface  of  the  lobe.  To  the 
left  of  the  gastric  artery  a  small  prolongation  is  wedged  in  between  the  arch  of  the  colon  and  the 
first  stomach,  its  extremity  just  touching  the  spleen.  This  portion,  or  tail  of  the  pancreas,  is 
wholly  non-peritoneal  and  adheres  to  the  organs  with  which  it  is  in  contact.  The  ventral  surface 
of  this  division,  body  and  tail,  falls  into  two  parts.  The  caudal,  in  its  whole  length,  is  adherent 
to  the  ascending  colon  and  the  colic  arch.  The  rostral  is  covered  by  peritoneum  of  the  lesser 
sac,  which  separates  it  from  the  stomach,  save  that  the  region  between  the  gastric  and  hepatic 
arteries,  forming  the  base  of  the  triangular  dorsal  area  and  corresponding  in  a  general  way  to 
the  body  of  the  more  usual  type  of  pancreas,  is  broadly  adherent  to  the  liver  in  the  region  of 
the  transverse  fissure  and  the  base  of  the  Spigelian  lobe.  The  Spigelian  recess  is  obliterated 
except  in  relation  to  the  enormous  papillary  process,  which  retains  its  peritoneal  covering.  This 
transverse  lobe  of  the  pancreas,  extending  from  the  ampulla  duodeni  to  the  spleen  forms  with 
the  ventrally  placed  stomach  the  boundary  of  a  transversely  oval  retrogastric  space,  into  which 
projects  the  processus  papillaris,  by  which  it  is  all  but  completely  filled.  This  is  the  only  portion 
of  the  liver  which  retains  a  covering  by  peritoneum  of  the  lesser  sac,  and  from  its  periphery 
reflection  takes  place  upon  the  stomach,  colon  and  gastric  surface  of  the  pancreas. 

The  sagittal  portion  of  the  pancreas  in  dorsal  view  is  bounded  by  the  descending  and  trans- 
verse portions  of  the  duodenum  and  to  the  left  by  the  root  of  the  mesentery.  The  left  portion 
of  this  surface  is  adherent  to  the  postcava,  which  descends  here  with  a  strong  inclination  to  the 
left.  The  right  portion,  more  than  half  of  the  dorsal  surface,  is  covered  by  peritoneum.  The 
portal  vein,  formed  by  the  junction  of  the  gastric  and  superior  mesenteric,  is  lodged  in  the  deep 
groove  between  the  two  divisions  of  the  pancreas,  and  is  directed  nearly  horizontally  to  the  right. 
Here  it  is  not  only  in  contact  with  the  postcava  immediately  prior  to  its  entrance  into  the  liver, 
but  the  two  veins  are  adherent  to  one  another,  entailing  as  a  consequence  the  obliteration  of 
Winslow's  foramen.  Ventrally  this  lobe  of  the  pancreas  is  concealed  by  the  ascending  colon, 
except  its  most  rostral  portion,  where  it  joins  the  transverse  division,  and  this  is  adherent  to  the 


454  SCHULTE,  SEI  WHALE. 

region  of  the  hepatic  hilum  ventral  to  the  portal  vein.  The  ducts  of  the  pancreas  were  not 
examined. 

Spleen. —  The  spleen  is  small  and  attached  closely  to  the  fundus  of  the  first  stomach  by  a 
duplicature  of  the  peritoneum  of  the  greater  sac.  It  is  elongated  and  narrow,  nearly  trans- 
verse in  position,  its  dorsal  extremity  prolonged  to  touch  the  pancreas.  To  the  right  it  lay  in 
peritoneal  contact  with  the  descending  colon.  The  lesser  sac  failed  to  reach  it. 

Adrenals. —  The  left  adrenal  is  oval,  dorso-ventrally  flattened,  with  a  feebly  convex  mesal 
border,  notched  a  little  above  its  middle.  This  notch  is  prolonged  as  a  furrow  on  the  ventral 
surface  where  the  adrenal  vein  emerges  from  it  and  descends  to  join  the  left  renal  vein.  The 
body  rests  against  the  left  crus  of  the  diaphragm  slightly  overlapping  the  left  kidney;  its  lower 
pole  is  in  contact  with  the  renal  vein  as  it  emerges  from  the  kidney.  Along  its  mesal  border 
it  is  adherent  to  the  duodenum,  the  remainder  of  the  ventral  surface  being  covered  by  perito- 
neum. The  arteries  enter  its  dorsal  surface  and  are  three  in  number,  a  branch  from  the  aorta, 
a  twig  from  the  renal  to  its  caudal  portion,  another  from  the  phrenic,  rostral  to  the  aortic  branch. 
Its  dimensions  are:  length  10.5  mm.;  breadth  6  mm.;  thickness  2.5  mm.  The  right  adrenal  is 
more  triangular  in  shape.  Resting  against  the  right  crus  of  the  diaphragm,  it  is  wedged  in 
between  the  postcava,  the  right  kidney  and  the  renal  vein. '  Ventrally  it  is  covered  with  peri- 
toneum save  that  a  strip  along  the  mesal  border  is  adherent  to  duodenum  and  at  the  upper  pole 
to  the  liver.  The  adrenal  vein  enters  the  postcava.  The  right  adrenal  is  of  about  the  same  size 
as  the  left  but  of  slightly  different  proportions.  Its  length  is  9  mm.,  its  breadth  6,  its  thickness 
3  mm. 

Peritoneum. —  It  has  been  seen  that  the  intestines  have  undergone  a  typical  complete  rota- 
tion to  the  left  beneath  the  arch  of  the  colon,  a  condition  which  Weber  l  has  found  to  be 
characteristic  of  the  Mysticete  in  contrast  to  the  Odontocete.  He  has  also  pointed  out  the 
non-development  or  rudimentary  condition  of  the  transverse  colon,  which  he  is  inclined  to  find 
represented  by  the  arch  between  the  oblique  ascending  and  the  descending  colon.  It  would 
appear  preferable  however  in  the  light  of  other  investigations,2  especially  those  dealing  with  the 
development  of  the  alimentary  canal  to  interpret  this  arch  of  the  colon  as  the  splenic  flexure, 
for  this  is  present  at  a  period  long  antecedent  to  the  differentiation  of  a  transverse  colon  and 
is  one  of  the  fixed  and  almost  invariable  landmarks  of  the  intestinal  tract.  It  represents  the 
apex  of  the  third  of  the  fundamental  intestinal  loops,  the  left  colic  of  Bardeen,  and  at  the  comple- 
tion of  rotation,  or  even  when  it  fails  to  occur,  regularly  swings  to  the  left  and  becomes  fixed 
below  the  spleen.  The  remainder  of  the  colon  at  this  period  occupies  an  oblique  position  along 
the  under  surface  of  the  right  lobe  of  the  liver,  and  only  with  the  secondary  growth  of  the  abdo- 
men and  the  diminution  of  the  bulk  of  the  liver,  gains  space  for  the  development  of  an  hepatic 
flexure,  which  establishes  the  limits  of  the  ascending  and  transverse  colon,  these  differentiating 
out  of  the  early  oblique  colon  limb  rather  than  by  growth  of  the  splenic  flexure.  Apart  from 
this  point  of  interpretation,  the  general  arrangement  of  the  bowel  conforms  closely  to  the  descrip- 
tion of  Hunter  3  and  the  more  detailed  study  of  Weber.4  As  the  ileo-colic  junction  faces  to  the 

1  Weber,  Max.     Studien  tiber  Saugethiere.     II.     Jena,  1886.     Die  Saugethiere.     Jena,  1904. 

2  Huntington,  Geo.  S.     Studies  in  the  development  of  the  alimentary  canal.     Report  of  the  Lying-in-Hospital  of  the  City  of  New 
York.     1893.     The  anatomy  of  the  human  peritoneum  and  abdominal  cavity.     Philadelphia  and  New  York.     1903.     Bardeen,  C.  R. 
The  critical  period  in  the  development  of  the  intestines.     Am.  Jour.  Anat.,  Vol.  16,  No.  4,  1914. 

3  Hunter,  John.,  op.  oil. 
*  Weber,  Max.,  op.  cit. 


SCHULTE,  SEI  WHALE.  455 

left  it  is  evident  that  the  axial  rotation  of  the  proximal  colon  has  occurred.  We  are  therefore 
dealing  with  a  developed  type  of  intestinal  arrangement,  in  which  the  fundamental  stages  of 
rotation  have  been  carried  to  completion.  The  secondary  changes  in  the  large  intestine  how- 
ever are  retarded  or  suppressed,  there  is  no  sigmoid,  the  differentiation  of  the  transverse  colon 
is  not  effected,  the  arched  colon  remaining  primitive  in  form,  and  further  the  characteristics 
of  the  higher  type  of  colon,  the  haustra,  are  lacking.  On  the  other  hand,  the  small  intestine 
has  lengthened  enormously.  Secondary  peritoneal  adhesions  in  the  course  of  the  intestine  are 
present,  but  in  the  infracolic  region  they  are  of  small  extent.  The  primary  root  of  the  mesentery 
is  retained  and  is  confined  by  the  arch  of  the  duodenum.  The  ascending  duodenum  with  the 
left  extremity  of  the  transverse  portion  have  lost  their  mesenteries,  as  has  also  the  splenic  flexure 
of  the  colon.  In  addition  the  ascending  limb  of  the  colon  has  contracted  an  unusual  adhesion 
to  the  venter  of  the  pancreas,  which  I  take  to  be  a  character  of  these  whales.  This  is  the  sole 
departure  from  the  common  type  of  mammalian  arrangement  in  this  region  of  the  abdomen, 
and  seems  to  depend  upon  the  early  loss  of  the  mesocolon,  which  it  may  be  noted  is  very  short 
in  the  whole  length  of  the  colon  below  the  duodenum. 

In  the  supracolic  region  on  the  contrary  there  are  many  peculiarities  which  seem  to  find 
their  explanation  in  the  crowding  of  the  abdominal  viscera  into  the  preumbilical  space.  This 
has  resulted  in  increased  adherence  of  viscera  to  one  another  and  to  the  diaphragm,  which  as 
they  have  taken  place  at  the  expense  of  the  lesser  sac,  have  materially  reduced  the  extent  of 
that  region  of  the  peritoneum.  The  chief  changes  thus  induced  are  the  reduction  of  the  Spige- 
lian  recess  by  the  increased  adherence  of  the  liver  to  the  diaphragm,  and  the  obliteration  of  the 
foramen  of  Winslow  by  the  approximation  of  the  portal  vein  to  the  postcava  and  the  adhesion 
of  the  pancreas  to  the  region  of  the  transverse  fissure.  The  splenic  recess  has  also  disappeared. 

The  lines  of  reflection  of  the  peritoneum  from  the  posterior  paries  of  the  upper  abdomen 
are  shown  in  Plate  LI,  Fig.  1,  and  the  corresponding  non-peritoneal  area  of  the  visceral  complex 
in  Plate  LII,  Fig.  3,  the  peritoneal  relations  of  the  liver  in  Plate  LII,  Fig.  4.  With  the  excep- 
tion of  the  covering  of  the  processus  papillaris  in  the  last  cited  figure  all  the  peritoneum  shown 
is  of  the  greater  sac.  With  the  aid  of  these  illustrations  we  may  proceed  to  trace  the  parietal 
visceral  lines  of  reflection.  From  the  right  of  the  postcava  at  the  diaphragm  the  line  descends 
to  the  upper  part  of  the  kidney,  then  turns  at  a  sharp  angle  to  the  left  and  rostrad  towards  the 
postcava  again  at  its  emergence  from  the  liver.  We  have  thus  bounded  the  surface  of  dia- 
phragmatic adhesion  of  the  right  lobe;  the  angle  of  this  area  is  not  prolonged  by  a  coronary  fold. 
The  caudal  limit  of  this  field,  the  line  from  this  angle  to  the  postcava  at  its  emergence,  marks  a 
reflection  from  liver  to  kidney  and  adrenal.  The  greater  part  of  the  latter  is  however  covered 
by  parietal  peritoneum  which  separates  it  from  the  descending  duodenum  and  the  pancreas,  so 
far  as  the  latter  is  free  dorsally.  From  the  postcava,  the  line  of  reflection  again  turns  caudad 
and  laterad  to  the  duodenal  impression  on  the  right  kidney,  at  the  upper  margin  of  which  it  begins 
to  turn  to  the  left  and  having  reached  the  lower  margin  of  this  impression  in  an  obliquely 
curved  course  becomes  continuous  with  the  line  of  attachment  of  the  right  leaf  of  the  mesentery. 
The  line  from  cava  to  duodenal  impression  marks  the  reflection  from  adrenal  and  kidney  to 
pancreas,  that  crossing  the  impression,  from  kidney  to  duodenum. 

To  the  left  of  the  cava  at  the  diaphragm  begins  the  very  large  left  coronary  ligament,  which 
after  extending  laterad  and  caudad  as  far  as  the  tenth  rib,  returns  on  itself  almost  to  the  cava. 
Turning  again  laterad  it  passes  in  front  of  the  oesophageal  orifice  and  assuming  a  sagittal  course 


.(.-,(;  SCHULTE,  SEI  WHALE. 

with  sinistral  convexity,  at  about  the  level  of  the  emergence  of  the  postcava  turns  mesad,  and 
again  taking  a  general  longitudinal  direction  curves  gradually  into  the  line  of  attachment  of  the 
left  leaf  of  the  mesentery.  From  the  coronary  ligament  to  the  mesal  turn  the  reflection  is  from 
the  diaphragm  to  the  first  stomach,  passing  at  this  point  immediately  rostrad  of  the  spleen. 
The  remaining  portion  marks  the  reflection,  first  from  diaphragm  to  colon,  and  then  from  left 
adrenal  to  ascending  duodenum. 

In  the  non-peritoneal  area  thus  bounded  are  exposed  on  the  posterior  parietes,  the  pillars 
of  the  diaphragm,  which  are  in  contact  with  the  Spigelian  lobe  of  the  liver  and  the  oesophagus; 
to  the  left  an  area  of  diaphragm  adherent  to  the  right  portion  of  the  first  stomach,  and  higher 
up  the  linear  space  for  the  left  coronary  ligament.  The  aorta  immediately  on  its  emergence 
from  the  arch  of  the  diaphragm  gives  origin  in  quick  succession  to  the  coeliac  axis  and  superior 
mesenteric  arteries,  these  branches  being  lodged  in  grooves  on  the  dorsum  of  the  pancreas.  To 
the  left  of  the  aorta,  the  left  adrenal  is  partially  exposed  and  is  in  apposition  with  the  ascending- 
duodenum.  The  postcava  as  far  as  its  bifurcation  between  the  upper  poles  of  the  kidneys  is 
retroperitoneal  and  has  ventral  to  it  the  superior  mesenteric  vessels,  the  portal  vein  and  par- 
tially the  pancreas.  While  to  the  right  of  the  cava  again  a  strip  of  adrenal  is  exposed  which 
is  apposed  to  pancreas.  Finally  to  the  right  of  the  caval  line,  from  the  diaphragm  to  the  begin- 
ning of  its  subhepatic  portion,  is  a  large  triangular  exposure  of  the  diaphragm.  It  deserves 
emphasis  that  on  the  right  the  peritoneum  of  the  greater  sac  approaches  the  cava  and  portal 
vein  at  the  transverse  fissure  of  the  liver,  but  is  here  reflected  from  these  vessels  and  the  rudi- 
mentary caudate  lobe  between  them  to  the  upper  extremities  of  the  right  adrenal  and  of  the 
vertical  pancreas. 

As  the  foramen  of  Winslow  is  obliterated  and  there  is  complete  separation  of  the  two  peri- 
toneal cavities,  it  is  convenient  to  treat  of  conditions  in  the  ventral  mesogastrium  first  with 
reference  to  the  greater  sac  alone.  We  have  here  to  consider  the  falciform  ligament  and  the 
reflection  of  peritoneum  from  the  liver  upon  the  upper  abdominal  visceral  complex.  The  falci- 
form ligament  departs  from  the  typical  condition  only  in  the  duplicity  of  the  umbilical  vein 
in  its  caudal  margin.  It  is  attached  to  the  ventral  parietes  in  the  midline  from  the  caval  orifice 
in  the  diaphragm  to  the  umbilicus,  and  to  the  liver  from  the  caval  emergence  to  the  deep  notch 
in  the  caudal  border  which  lodges  the  umbilical  veins.  It  is  broad  and  strong  and  in  this  fretus 
directed  distinctly  to  the  left  in  its  passage  from  abdominal  wall  to  liver.  The  hepato-visceral 
reflection  of  the  greater  sac  comprises  from  left  to  right  the  line  of  the  outer  layer  of  the  gastro- 
hepatic  omentum  and  the  hepato-duodenal  fold.  In  the  region  of  the  obliterated  epiploic  foramen 
there  is  a  recess  of  the  greater  sac,  of  triangular  form,  with  the  postcava  and  portal  vein  at  its 
apex.  It  is  shown  in  the  figure  of  the  dorsal  surface  of  the  liver  (Plate  LII,  Fig.  4)  as  a  reentrant 
angle  with  its  apex  abutting  on  the  postcava  to  the  left  of  the  diaphragmatic  area.  This  recess 
must  not  be  confused  with  the  larger  retro-duodenal  fossa  formed  by  the  hepato-renal  and 
pancreatico-adrenal  folds,  which  also  has  its  apex  upon  the  postcava  (Plate  LII,  Fig.  3).  The 
two  are  separated  by  duodenum  and  pancreas,  and  the  one  now  considered  is  preduodenal  in 
position  and  of  much  less  extent.  In  this  reflection  we  have  to  the  left  and  ventrally,  the  hepato- 
duodenal  fold,  which  in  the  typical  conformation  of  the  region  forms  the  free  edge  of  the  gastro- 
hepatic  omentum  and  contains  the  portal  vein,  hepatic  artery  and  bile  duct,  thus  forming  the 
ventral  boundary  of  the  foramen  of  Winslow,  the  remaining  boundaries  being  the  caudate  lobe 
above,  the  cava  behind,  the  duodenum  below.  By  the  adherence  of  the  two  veins  the  fora- 


SCHULTE,  SEI  WHALE.  457 

men  is  closed  and  the  peritoneum  of  the  greater  sac  passes  uninterruptedly  over  the  cava  from 
the  portal  vein,  so  that  the  gastro-duodenal  ligament  receives  an  extension  to  the  right  and 
dorsad,  and  one  can  follow  the  anterior  layer  of  the  gastro-hepatic  omentum  continuously  from 
portal  vein  over  postcava  to  adrenal  and  abdominal  wall,  passing  in  a  horizontal  direction  from 
left  to  right.  From  above  downwards  the  reflection  is  from  portal  vein,  caudate  lobe  and  cava 
to  the  ampulla  duodeni.  Thus  the  free  edge  of  the  gastro-hepatic  omentum  is  lost  and  the  site 
of  the  primitive  foramen  is  marked  only  by  a  shallow  preduodenal  recess. 

The  remainder  of  the  anterior  layer  of  the  gastro-hepatic  omentum  follows  the  usual  line 
of  reflection  from  the  transverse  fissure  and  that  of  the  ductus  venosus;  it  is  peculiar  only  in 
its  angular  extension  upon  the  proximal  portion  of  the  umbilical  fissure,  occasioned  by  the 
extensive  adherence  of  the  pancreas  to  the  liver  in  this  region.  This  has  been  accomplished 
by  the  extension  of  the  pancreas  into  the  gastro-hepatic  omentum,  with  the  consequence  of 
first  separating  its  layers,  secondarily  of  effecting  adhesions  in  the  reduplicature  of  the  ental 
layer  interposed  between  liver  and  pancreas,  and  ultimately  entailing  obliteration  of  much 
of  the  retrogastric  space.  As  a  consequence  of  this  process  only  the  ectal  layer  of  the  omentum 
is  retained  in  its  transverse  segment,  and  this  is  reduced  to  a  mere  reflection  of  peritoneum  from 
the  liver  to  the  lesser  curvature  of  the  fourth  and  third  gastric  compartments,  which  are 
closely  attached  to  the  undersurface  of  the  gland.  Only  beside  the  papillary  process  does 
the  vertical  segment  retain  its  two  layered  condition,  and  only  here  has  the  gastro-hepatic 
omentum  an  appreciable  length,  spreading  out  from  its  attachment  upon  the  liver  to  the  lesser 
curvature  of  the  second  stomach.  Above  the  papillary  process  the  omentum  becomes  reduced 
again  to  a  single  layer  —  the  consequence  of  the  obliteration  in  large  part  of  the  Spigelian 
recess  —  and  here  again  it  is  a  mere  reflection  from  liver  to  first  stomach. 

Arrived  at  the  lesser  curvature  the  ectal  layer  of  the  gastro-hepatic  omentum  passes  over 
the  ventral  surface  of  the  stomach  to  the  greater  curvature  of  the  second,  third  and  fourth  com- 
partments and  thence  descends  as  the  ectal  layer  of  the  great  omentum.  Turning  at  its  margin 
it  ascends  to  the  margin  of  the  pancreas  that  intervenes  between  its  colic  and  gastro-hepatic 
surfaces  and  is  there  reflected  caudad  upon  the  colon,  whence  it  may  be  traced  to  the  right  leaf 
of  the  mesentery.  Upon  the  first  compartment  of  the  stomach  it  passes  to  the  fundus  and  there 
is  reflected  over  the  spleen  as  the  gastro-splenic  omentum,  for  here  again  the  lesser  sac  is  lack- 
ing and  the  region  of  the  hilus  is  not  in  peritoneal  contact  with  the  stomach  but  is  adherent 
to  it.  Beyond  the  spleen  the  line  of  this  reflection  ascends  on  the  one  hand  to  the  angle  between 
the  first  and  second  compartments,  and  on  the  other  skirts  the  colic  area  of  the  fundus  to  the 
transverse  division  of  the  pancreas,  at  both  of  these  points  joining  the  lines  of  omental  reflection 
that  have  already  been  described. 

The  lesser  sac,  it  has  already  been  pointed  out,  is  peculiar  in  the  loss  of  the  foramen  of 
Winslow,  the  obliteration  of  the  splenic,  and  the  reduction  of  the  Spigelian  recesses.  These 
changes  are  undoubtedly  secondary  and  associated  with  the  collocation  of  viscera  in  the  pre- 
umbilical  region.  The  lesser  sac  as  a  result  is  reduced  to  a  relatively  simple  retrogastric  space 
and  the  cavity  of  the  great  omentum.  Their  mutual  boundary  is  given  by  the  attachment 
of  the  great  omentum,  which  has  already  been  traced  in  the  description  of  its  ectal  layer.  It 
is  shown  in  Plate  LIT,  Fig.  1. 

The  great  omentum  was  crumpled  into  a  mass  which  lay  at  the  greater  curvature  of  the 
stomach,  to  the  left  of  the  falciform  ligament  and  above  the  coils  of  the  small  intestine.  It 


458  SCHULTE,  SET  WHALE. 

was  very  delicate  and  gave  away  when  the  attempt  was  made  to  straighten  it  out,  so  that  its 
extent  could  not  be  ascertained.  It  seemed  of  moderate  size,  but  I  do  not  think  it  would  have 
reached  to  the  umbilicus. 

The  retrogastric  space  is  invaginated  from  above  by  the  processus  papillaris,  which  com- 
pletely fills  the  oval  between  the  stomach  and  the  pancreas  extending  caudad  as  far  as  the  colon. 
The  cavity  has  then  something  of  the  shape  of  an  oval  dish  with  its  marge  applied  to  the  peri- 
phery of  the  papillary  process.  Here  the  reflection  of  its  peritoneum  takes  place,  ventrad  and 
to  the  left  as  the  ental  layer  of  the  gastro-hepatic  omentum  to  the  lesser  curvature  and  thence 
over  the  dorsal  surface  of  the  stomach  into  the  omentum;  to  the  right  and  dorsad  upon  the 
transverse  pancreas  and  then  into  the  dorsal  wall  of  the  omentum.  From  a  comparison  of  the 
line  of  reflection  at  the  papillary  process  and  that  of  the  great  omentum,  it  is  seen  that  the  retro- 
gastric  space  broadens  markedly  caudad.  I  could  not  find  an  extension  of  the  lesser  sac  upon 
the  right  of  the  oesophagus  corresponding  to  the  isolated  cavity  here  present  in  Tursiops,  nor 
could  I  ascertain  that  it  reached  the  dorsal  paries  at  any  point. 

In  the  whales  it  is  evident  that  very  peculiar  relations  obtain  in  the  topography  of  the 
upper  abdomen  and  in  the  disposition  of  its  peritoneum.  Hunter  first  described  the  obliteration 
of  the  foramen  of  Winslow.  "In  some  of  this  tribe  there  is  the  usual  passage  behind  the  vessels 
going  to  the  liver,  common  to  all  quadrupeds  I  am  acquainted  with;  but  in  others,  as  the  small 
Bottle-nose,  there  is  no  such  passage,  which  by  the  cavity  becomes  a  circumscribed  cavity." 
He  does  not  specify  further  the  forms  in  which  the  foramen  persists,  nor  have  I  in  the  literature 
as  yet  come  upon  another  reference  to  this  condition.  It  is  evident  however  that  members 
of  both  suborders  concur  in  this  obliteration,  and  in  Tursiops  truncatus,  of  which  I  had  the 
opportunity  at  the  New  York  Aquarium  to  examine  three  specimens,  there  is  also  reduction  of 
the  lesser  sac  in  the  loss  of  the  splenic  and  the  all  but  complete  obliteration  of  the  Spigelian  recess. 
Taken  in  conjunction  with  the  wide  differences  between  the  suborders  in  the  infracolic  com- 
partment as  pointed  out  by  Weber  this  resemblance  is  of  some  theoretic  interest.  For  under 
conditions  which  are  sufficient  to  produce  in  both  the  highly  peculiar,  and  probably  unique, 
modifications  of  the  lesser  sac,  the  divergent  evolution  of  the  lower  digestive  tract  is  evidence  of 
the  plasticity  of  the  alimentary  canal,  and  its  potentiality  of  highly  diverse  modification 
within  the  limits  of  a  single  order.  The  major  peculiarity  is  undoubtedly  the  reduction  of  the 
lesser  sac,  and  may  find  its  determining  factors  in  the  crowding  of  the  upper  abdomen  by  the 
huge  liver  and  stomach  under  pressure  from  without,  even  though  the  extreme  forward  displace- 
ment of  the  intestine  of  the  Balsenoptera  foetus  is  not  present  in  a  somewhat  larger  foetus  of 
Tursiops,  which  has  been  examined  for  this  point.  Here  however  the  relatively  enormous  liver, 
with  its  massive  left  lobe,  had  effected  even  a  greater  degree  of  crowding  of  the  viscera  in  the 
upper  abdomen,  although  the  intestine  was  largely  postumbilical  in  position.  The  primary 
condition,  operative  with  differing  details  in  both,  would  seem  to  be  the  torpedo-form  of  the 
body,  with  its  major  girth  located  in  the  preumbilical  region. 


SCHULTE,  SEI  WHALE.  459 

UROGENITAL  APPARATUS. 
(Plate  LI,  Fig.  1,  LI  I,  Figs.  1,  2.} 

The  urinary  and  reproductive  organs  of  Balcenoptera,  apart  from  descriptions  contained 
in  reports  of  individual  specimens,  have  been  the  subject  of  more  particular  investigation  on 
the  part  of  Beauregard  and  Boulart,1  and  more  recently  of  Daudt,2  to  whom  we  owe  a  most 
thorough  and  critical  study  of  these  organs  in  the  Cetacea.  In  most  respects  conditions  in  this 
fcetus  closely  resemble  his  descriptions  of  B.  musculus;  there  are,  however,  some  differences  of 
which  the  most  important  is  the  mode  of  fixation  of  the  kidneys. 

Kidneys. —  These  organs  are  adherent  to  the  parietes  in  the  whole  extent  of  their  dorsal 
surfaces,  and  not  suspended  from  their  mesal  borders  as  in  the  older  fcetus  of  Daudt  (length 
104  cm.  cf,  cf.  his  text  figs.  4,  5  and  6).  On  the  contrary  the  peritoneum  passes  over  the  kidneys 
from  the  mesentery  to  their  lateral  margins  and  thence  to  the  abdominal  walls  in  the  manner 
usual  in  mammals  and  as  in  Eschricht's  3  fcetus  of  B.  rostrata.  This  seems  also  to  have  been 
the  case  in  Daudt's  younger  fcetus  (length  50  cm.).  I  could  not  detect  on  either  side  a  muscular 
connection  with  the  diaphragm.  The  kidneys  are  slightly  asymmetrical,  the  right  lying  farther 
rostrad  and  overlapping  by  its  upper  pole  the  origin  of  the  diaphragm,  while  the  left  just  falls 
short  of  reaching  the  diaphragm.  The  degree  of  asymmetry  in  this  fcetus  is  thus  very  small, 
but  is  in  the  same  sense  as  in  Daudt's  fcetus  and  is  additional  evidence  that  the  greater  bulk 
of  the  liver  on  the  left  is  not  the  determining  factor  in  the  position  of  the  kidneys,  when  as  so 
generally  happens  in  mammals  the  right  is  slightly  lower  than  the  left.  In  addition  to  the  peri- 
toneum which  covers  their  ventral  surfaces  the  kidneys  are  invested  by  a  thick  and  strong  fascia 
renalis,  which  in  this  preserved  fcetus  is  somewhat  redundant  and  masks  the  real  shape  of  the 
kidneys,  causing  them  to  appear  larger  and  more  plump  than  actually  they  are.  Upon  this 
thick  investment  of  the  kidney  are  the  impressions  of  the  duodenum  at  the  upper  pole  and  of 
the  colon  in  the  rostral  half  of  the  mesal  border  on  the  right  side,  and  of  the  colon  again  on  the 
left  side  along  its  mesal  border  caudad.  But  the  kidneys  themselves  show  no  traces  of  contact 
with  these  organs  upon  the  removal  of  their  capsules.  The  fascia  renalis  has  much  the  same 
arrangement  as  Gerota  *  has  described  for  man.  Its  ventral  layer  crosses  the  aorta  and  post- 
cava  to  become  continuous  with  that  of  the  opposite  side.  The  dorsal  layer  is  easily  stripped  up 
from  the  sheath  of  the  hypaxial  muscle  to  near  its  mesal  border,  where  it  becomes  firmly  adher- 
ent. Somewhat  lateral  to  the  kidney  the  two  layers  unite  and  are  continued  as  the  endabdominal 
fascia.  Rostrad  the  adrenal  is  included  between  the  layers,  which  fusing  are  continued  as 
the  very  thick  fascia  on  the  abdominal  surface  of  the  diaphragm.  Caudad  they  are  continued 
dorsal  and  ventral  to  the  ureter,  and  here  fat  appears  between  them  for  the  first  time.  They 
now  become  thinner  and  difficult  to  follow  and  apparently  are  lost  as  in  man  in  the  areolar  tissue 
of  the  region. 

Beneath  the  fascia  renalis  the  kidney  is  invested  by  a  thin  transparent  tunica  fibrosa.  This 
is  without  much  difficulty  resolvable  into  two  layers,  one  relatively  thick  and  strong  of  super- 


1  Beauregard  and  Boulart.     Recherches  sur  les  appareils  genito-urinaires  des  Batenopterides.    Jour,  de  1'Anat.  ot  de  la  Phys.,  An. 
XVIII,  1882. 

2  Daudt,  Wm.     Beitrage  zur  Kenntins  des  Urogenitalapparates  der  Cetaceen.     Jena,  Zeitsch.  f.  Naturwiss.,  Bd.  XXXII,  1898. 

3  Eschricht.     Zool.-anat.-phys.     Untewuchungan  iibar  die  nordischen  Waltiere.     Leipzig,  1849. 

*  Gerota,  D.     Beitriige  zur  Kcatniss  des  Befestigungsapparates  der  Niere.     Arch.  f.  Anat.  und  Entwickel.,  Jahr.  1895,  p.  265. 


460  SCHULTE,  SEI  WHALE. 

ficial  position,  the  other  extremely  delicate  investing  the  individual  renculi  and  sending  septa 
between  them  into  the  interior  of  the  organ.  These  are  both  recognized  and  described  by  Daudt, 
who  terms  the  ectal  one  the  capsula  fibrosa,  the  ental  tunica  albuginea.  In  addition  to  these 
delicate  septa,  coarser  ones  are  present  surrounding  groups  of  lobules,  and  in  these  both  layers 
of  the  tunica  fibrosa  appear  to  participate.  I  have  not  however  verified  this  point  histologically. 
Of  these  latter  by  far  the  largest  and  strongest  is  on  the  ventral  surface  extending  from  the 
point  of  entry  of  the  renal  artery  to  the  emergence  of  the  ureter.  There  thus  is  in  addition  to 
the  renculus,  a  larger  architectural  unit  composed  of  groups  of  renculi,  defined  by  coarser  con- 
nective tissue  septa,  and  this  type  of  organization  appears  to  be  an  additional  difference  between 
the  kidney  of  the  mystacete  and  that  of  the  odontocete  with  its  smaller  number  of  renculi.  These 
groups  are  irregular  in  shape  and  variable  in  the  number  of  renculi  they  contain.  There  is  a 
tendency  on  the  ventral  and  dorsal  surfaces  to  the  rectangular  form  with  longitudinal  and  trans- 
verse septa;  laterally  the  arrangement  becomes  wholly  irregular.  The  number  of  renculi  in 
a  group  varies  between  seven  and  thirty,  but  a  large  majority  of  the  groups  are  composed  of  nine 
to  fifteen.  In  size  the  individual  renculi  varied  between  1  and  1.5  mm.  A  rough  count  of  the 
number  in  the  left  kidney,  the  smaller  of  the  two  yielded  1350.  This  is  far  below  the  count 
of  Beauregard  and  Boulart,  3000,  and  Daudt  states  his  own  counts  to  have  been  but  little  less. 
In  this  connection  the  process  of  increase  becomes  important.  Nearly  half  of  the  renculi  in 
this  kidney  show  signs  of  subdivision,  into  two,  three  or  even  four  parts.  A  count  of  100  showed 
60  to  be  simple,  30  divided  by  a  sulcus  into  two  parts,  6  into  three,  and  4  into  four.  If  all  these 
subdivisions  were  actually  accomplished,  the  count  would  be  still  a  third  less  than  that  of 
Beauregard  and  Boulard. 

The  right  kidney  has  a  length  of  35  mm.  Its  greatest  breadth  and  thickness  coincide  with 
the  level  of  its  penetration  by  the  blood  vessels;  the  former  dimension  is  18.5  mm.,  the  latter 
9.5  mm.  Caudad  of  the  vessels  the  organ  diminishes  in  breadth  to  the  rounded  caudal  pole, 
the  margins  being  straight;  the  mesal  is  blunt,  but  the  lateral  is  expanded  to  a  surface  well 
defined  from  the  dorsal  and  ventral  faces.  It  is  well  shown  in  Daudt's  l  schematic  cross-section. 
Rostral  to  the  vessels  the  ventral  surface  is  beveled  off  so  that  it  looks  rostrad  and  laterad  as 
well  as  ventrad;  here  it  is  in  contact  with  the  liver.  In  the  region  of  the  vessels  and  separated 
from  the  hepatic  surface  by  a  sagittal  prominence  a  small  area  is  directed  mesad,  ventrad  and 
slightly  rostrad,  which  is  in  contact  with  the  duodenum  and  coils  of  the  small  intestine.  The 
borders  of  the  kidney  rostrad  converge  almost  to  a  point,  which  is  inserted  between  the  liver 
and  the  adrenal. 

The  left  kidney  is  appreciably  smaller  than  the  right,  measuring  32  mm.  in  length,  14  mm. 
in  breadth  and  9  mm.  in  thickness.  It  is  distinctly  more  slender,  its  margins  more  nearly  par- 
allel, and  it  lacks  the  marked  broadening  at  the  level  of  the  vessels.  In  consequence  the  lateral 
margin  lacks  the  angle  present  on  the  right  at  this  point.  The  rostral  pole  is  broadly  convex 
and  not  pointed.  The  lateral  surface  is  well  demarcated  from  the  flat  dorsum,  but  passes  into 
the  ventral  surface  by  a  gradual  curve. 

The  dorsal  surfaces  of  both  kidneys  are  nearly  flat  resting  against  the  hypaxial  muscles. 
Their  lateral  surfaces  are  in  apposition  with  loose  areolar  tissue,  which  fills  the  angular  space 
between  them  and  the  transversalis,  but  as  yet  no  fat  has  been  deposited  here.  The  ventral 


1  Op.  tit.,  text  fig.  4,  p.  274. 


PLATE  Lin. 


PLATE  LIII. 


Fig.  1. 
Fig.  2. 
Fig.  3. 
Fig.  4. 


Baltznoptera  borealis. 

Genital  tract,  dorsal  view.     Twice  natural  size. 
Postcava,  aorta  and  right  kidney.     Twice  natural  size. 
Left  lung,  lateral  view.     H  X  natural  size. 
Pylorus  and  ampulla  duodeni.     Twice  natural  size. 


1.  Umbilical  artery. 

2.  Bladder. 

3.  Ovary. 

4.  Cornu  of  uterus. 

5.  Body  of  uterus. 

6.  Vagina,  proximal  portion  with  folds. 

7.  Vagina,  distal  portion. 

8.  Ligamentum  latum. 

9.  Fold  for  ovarian  vessels. 

10.  Adrenal. 

11.  Kidney. 

12.  Ureter. 

13.  Cavo-vertebral  communication. 

14.  Adrenal  vein. 


15.  Renal  vein. 

16.  Phrenic  vein. 

17.  Right  postcava. 

18.  Left  postcava. 

19.  Inferior  mesenteric  artery. 

20.  Ovarian  arteries. 

21.  Caudal  artery. 

22.  Iliac  artery. 

23.  Groove  for  superior  intercostal  vein. 

24.  Stomach,  compartment  4. 

25.  Pylorus. 

26.  Ampulla  duodeni. 

27.  Orifice  of  bile  duct. 


.Memoirs  Am.  Mus.  Nat,  Hist. 


N.  S.,  Vol.  I,  Plate  LIU. 


Fig.  1. 


.  4- 


Fig.  2. 


Fig.  3. 


BAL^ENOPTERA  BOREALIS. 


SCHULTE,  SEI  WHALE.  461 

surfaces  are  inclined  mesad  below  the  entry  of  the  vessels;  the  colon  is  interposed  between  them 
dorsally,  the  bladder  and  hypogastric  arteries  ventrally.  Rostral  to  the  vessels  the  surface 
of  the  right  kidney  has  already  been  described;  that  of  the  left  is  convex  and  in  contact  with 
coils  of  the  small  intestine.  The  adrenal  is  applied  to  its  mesal  border. 

The  renal  veins  emerge  from  a  deep  groove  on  the  venter  of  the  kidney  in  its  rostral  fourth. 
The  distance  from  the  rostral  pole  to  the  vein  is  on  the  right  side  7  mm.,  on  the  left  5.5  mm. 
Both  veins  ascend  to  the  postcava,  the  left  much  more  steeply  than  the  right.  The  arteries  lie 
caudal  to  the  veins  which  do  not  overlap  them,  so  that  they  are  exposed  to  ventral  view  in  their 
whole  breadth.  The  ureters  emerge  ventrally  also  and  are  lodged  in  a  deep  groove  of  the  ventral 
surface  as  far  as  the  caudal  pole.  As  has  been  said  their  point  of  emergence  is  connected  by  a 
strong  septum  to  that  of  the  vein  and  artery.  From  the  ventral  position  of  these  structures  it 
is  clear  that  the  kidney  has  not  undergone  complete  rotation,  and  that  the  caudal  portion  has 
rotated  to  an  appreciably  less  degree  than  the  rostral,  for  the  ureter  is  almost  directly  ventrad, 
while  the  vessels  are  turned  a  little  further  in  a  mesal  direction. 

Ureters. —  The  ureters  emerge  from  the  ventral  surface  of  the  kidneys  near  their  caudal 
poles.  Here  they  are  received  in  grooves  in  the  kidneys  and  do  not  project  beyond  the  general 
level  of  the  surface.  Arrived  at  the  pole  they  make  a  short  bend  laterad  and  then  pass  with  a 
slightly  sinuous  course  caudad  at  the  same  time  inclining  mesad.  Arrived  at  the  sides  of  the 
dilated  portion  of  the  vagina,  they  curve  ventrad  to  the  sides  of  the  bladder,  in  contact  with 
which  they  ascend  rostrad  for  several  millimeters  before  piercing  its  walls.  As  they  do  this 
very  obliquely  and  the  muscularis  of  the  bladder  is  thick  they  have  a  long  intramural  segment. 
Their  orifices  are  close  together  on  the  fundus,  6  mm.  from  the  urethral  orifice,  each  at  the 
summit  of  a  longitudinal  ridge  which  corresponds  to  the  terminal  portion  of  the  ureter.  These 
ridges  are  separated  by  a  deep  notch  rostrad;  caudad  their  reliefs  merge  into  a  median  eleva- 
tion which  continues  to  the  urethral  orifice.  This  is  smooth,  the  mucous  membrane  adhering 
firmly  to  the  underlying  muscle,  and  represents  the  trigone.  From  the  notch  a  faint  median 
sulcus  is  prolonged,  which  partially  separates  it  into  two  halves.  The  elevations  upon  which 
the  ureters  open,  in  the  undisturbed  position  of  the  parts,  are  in  apposition  with  the  blunt 
extremities  of  longitudinal  folds  of  the  mucosa.  These  fit  close  against  the  apices  of  the 
ureteral  elevations,  and  would  seem  able  during  contraction  of  the  bladder  to  guard  against 
regurgitation  into  the  ureter. 

The  ureter  at  its  emergence  from  the  kidney  is  dorso-ventrally  flattened.  As  it  descends 
it  makes  a  spiral  turn,  as  Hyrtl  and  Daudt  have  observed,  and  in  such  a  direction  that  the 
ventral  surface  becomes  median.  As  it  enters  upon  its  longitudinal  course,  it  becomes  cylin- 
drical and  so  continues  to  its  termination.  It  diminishes  in  diameter  from  kidney  to  bladder, 
but  only  to  a  slight  degree.  As  Daudt  has  stated  it  is  invisible  through  the  peritoneum.  On 
leaving  the  kidney  it  is  placed  inside  the  tubular  prolongation  of  the  fascia  renalis,  within  which 
at  this  point  there  is  a  deposit  of  fat.  Distad  this  diminishes  and  the  ureter  is  surrounded  by 
firm  areolar  tissue  which  forms  the  continuation  of  the  renal  fascia.  This  separates  it  from 
the  peritoneum  as  it  passes  between  the  vagina  and  the  hypogastric  artery  to  reach  the  bladder. 
Of  course  it  does  not  break  through  the  peritoneum  to  do  this;  Daudt's  statement  to  that  effect 
must  be  an  oversight  in  the  correction  of  his  proof. 

Bladder.—  The  bladder  is  long  and  narrow,  extending  rostrad  almost  to  the  umbilicus 
before  it  is  reduced  to  the  urachus.  It  agrees  with  Daudt's  description  in  being  flattened  ven- 


462  SCHULTE,  SEI  WHALE. 

trally  and  strongly  convex  dorsally.  Its  length  is  32  mm.;  its  greatest  breadth  is  8  mm. 
Caudad  it  tapers  to  the  urethra,  the  diameter  beginning  to  be  reduced  from  the  level  of  the 
ureteral  orifices.  At  about  this  level  dorsally  the  peritoneum  is  reflected  from  it  upon  the 
uterus  and  broad  ligament.  Ventrally  it  is  loosely  adherent  to  the  abdominal  wall.  At  the  sides 
the  hypogastric  arteries  are  closely  united  to  its  walls  and  the  three  structures  are  enclosed 
within  a  common  sheath,  which  Daudt  finds  to  be  muscular.  At  the  umbilicus  the  arteries 
have  a  dorsal  position,  the  urachus  ventral.  The  muscularis  is  very  thick,  the  lumen  is  reduced 
to  a  narrow  cavity.  The  mucous  membrane  is  thrown  into  longitudinal  folds,  of  which  three 
are  conspicuous;  a  mid-dorsal  one  beginning  between  the  ureteral  orifices,  and  two  more  lateral 
in  position,  in  line  with  the  ureteral  elevations  and  approximated  to  them  in  the  manner  already 
described.  The  latter  are  continued  to  the  junction  with  the  urachus.  The  median  fold 
diminishes  rostrad,  and  gives  place  to  two  folds  one  on  each  side,  intermediate  between  it  and  the 
lateral  folds.  Ventrally  there  is  a  low  median  fold.  As  more  numerous  and  less  definitely 
arranged  folds  are  described  by  Daudt  in  older  fcetuses,  it  is  to  be  concluded  that  in  the  bladder 
as  in  the  alimentary  tract  in  general  a  few  primary  folds  are  secondarily  replaced  in  develop- 
ment by  more  numerous  and  smaller  ones. 

Urethra. —  The  urethra  is  very  long  having  a  length  of  23  mm.  to  its  external  orifice.  Its 
external  diameter  is  3  mm.  Its  lumen  stellate  at  its  junction  with  the  bladder  gradually  becomes 
a  transverse  slit  as  it  is  followed  distad.  Near  its  termination  it  is  about  1  mm.  in  breadth. 
Its  dorsum  is  flattened  against  the  vagina.  The  two  are  contained  in  a  common  fibrous  sheath, 
but  only  near  the  orifice  could  I  find  the  urethra  surrounded  by  the  circular  muscle  layer  of  the 
vagina. 

Ovaries. —  The  ovaries  rest  against  the  lower  poles  of  the  kidneys.  Ventral  to  them  are 
the  uterine  cor'nua,  which  the  elongated  ovaries  cross  obliquely  so  that  their  rostral  poles  are 
nearer  the  median  plane  than  their  caudal.  Only  a  small  portion  of  the  ovary  is  caudal  to  the 
horn  of  the  uterus  and  rests  against  the  broad  ligament.  Rostrad  of  the  cornu  the  left  ovary 
rests  against  the  hypogastric  artery  and  bladder,  the  right  against  the  artery  without  touching 
the  bladder.  Their  position  is  thus  slightly  asymmetrical,  the  right  ovary  being  somewhat  more 
ventral  and  rostral  than  the  left,  but  not  more  than  2  mm.  in  either  direction.  The  ovaries  are 
elongated,  tapering  at  their  rostral  poles,  more  bluntly  rounded  caudad,  attaining  their  great- 
est breadth  transversely  just  caudad  of  the  uterine  cornua  and  their  greatest  dorso-ventral  thick- 
ness just  rostrad  of  them.  In  these  three  dimensions  the  right  ovary  measures  10.5  mm.,  5  mm., 
and  3  mm.  respectively,  the  left  10  mm.,  4.5  mm.,  and  3  mm.  The  surface  shows  many  small 
pits  and  shallow  sulci  which  cut  it  up  into  polygonal  areas.  The  ventral  surface  is  deeply  con- 
cave to  receive  the  uterine  cornu.  The  convolutions  of  the  oviduct  are  laterally  placed  and  the 
summit  of  its  fimbriated  extremity  is  attached  to  the  rostral  pole  of  the  ovary.  The  true  and 
false  ligaments  about  the  ovary  in  Balcenoptera  have  been  described  by  Beauregard  and  Boulart  ' 
and  studied  in  more  detail  by  Daudt 2  in  B.  musculus.  Their  condition  in  this  foetus  agrees 
closely  with  the  findings  of  the  latter  investigator.  Each  ovary  has  a  slit-like  hilus  along  its 
lateral  border,  which  deepens  caudad  and  here  gives  passage  to  the  ovarian  vessels,  contained 
in  a  process  of  the  broad  ligament.  This  fold  which  is  very  short  constitutes  the  mesovarium. 


1  Beauregard  et  Boulart.     Recherches  sur  les  appareils  genito-urinaires  des  Balaenides.     Jour,  de  PAnat.  et  de  la  Phys.,  An.  XVIII, 
1882. 

-  Daudt,  W.     Beitrilge  zur  Kenntnis  des  Urogenitalapparates  der  Cetaceen.     Jena.  Zeitsch.  f.  Naturwiss.,  Bd.  XXXII,  1898. 


SCHULTE,  SEI  WHALE.  463 

Near  its  caudal  extremity  a  very  short  band  connects  the  caudal  pole  of  the  ovary  to  the  uterine 
cornu,  opposite  the  point  at  which  the  ligamentum  teres  begins.  For  this  reason  I  take  it  to 
be  the  ligamentum  ovarii.  Daudt  in  his  larger  foetus  describes  this  fold  as  passing  from  the 
junction  of  the  middle  and  last  thirds  of  the  ovary  to  the  cornu,  so  that  it  appears  to  shift  rostrad 
during  development.  The  short  transverse  fold,  which  he  describes  as  passing  from  ovary  to 
oviduct  between  this  ligament  and  the  ovarian  attachment  of  the  ostium  abdominale,  is  not  yet 
indicated.  The  plica  diaphragmatica  is  long  and  high.  It  attaches  to  a  convolution  of  the 
oviduct  close  to  the  ovary  and  extends  lateral  to  the  kidney  somewhat  beyond  its  rostral  pole. 

Oviduct. —  The  infundibulum  is  long  and  slit-like  with  even  margins,  forming  a  flattened 
funnel,  the  rostral  extremity  of  which  is  attached  to  the  ovary.  Its  interior  is  at  first  smooth, 
but  in  its  depth  becomes  marked  by  small  folds  and  furrows,  which  converge  towards  the  ampulla. 
The  oviduct  is  closely  convoluted,  its  turns  obscured  by  their  peritoneum.  Of  these  there  seems 
to  be  four  on  each  side.  As  a  whole  the  tube  has  a  general  sagittal  course  on  the  lateral  aspect 
of  the  ovary  and  terminates  by  turning  mesad  and  ventrad  to  join  the  uterine  cornu.  To  its 
commencement  is  attached  the  plica  diaphragmatica  already  mentioned. 

Uterus. —  The  uterus  consists  of  a  short  body  and  long  arched  cornua,  which  turning  laterad 
upon  the  ventral  surfaces  of  the  ovaries  diminish  rather  abruptly  in  diameter  and  are  continued 
as  the  oviducts.  Ectally  this  junction  is  marked  by  a  change  in  direction,  the  proximal  segment 
of  the  oviduct  forming  a  small  angular  bend  below  the  ostium  abdominale,  just  mesad  of  which 
it  enlarges  to  become  the  cornu.  Distad  the  cornua  are  in  contact  for  about  a  third,  of  their 
length  before  they  unite  to  form  the  body  of  the  uterus.  This  junction  is  perfectly  symmetrical 
in  external  view.  The  cornua  have  a  length  of  17  mm.  measured  along  their  convexity;  their 
diameter  is  3  mm.  The  body  of  the  uterus  is  short  measuring  from  the  union  of  its  cornua  to  the 
first  transverse  sulcus  of  the  vagina  only  6  mm.  Its  form  resembles  that  of  an  hour-glass, 
diminishing  to  about  its  middle  and  again  expanding  towards  the  vagina.  Ventrally  it  is  some- 
what flattened  against  the  bladder,  but  dorsally  it  is  strongly  convex.  The  cornua  and  broad  liga- 
ment also  rest  against  the  convex  dorsum  of  the  bladder,  and  curve  ventrad  upon  its  sides  so 
that  the  terminations  of  the  horns  rest  against  the  hypogastric  arteries.  Here  there  is  a  slight 
degree  of  asymmetry,  for  the  axis  of  the  uterus  deviates  from  the  midline  to  the  left  as  it  is  fol- 
lowed rostrad  and  in  consequence  the  left  cornu  is  at  its  termination  slightly  caudal  to  the  right. 
The  same  holds  true  of  the  ovary.  The  difference  between  the  two  sides  is  however  so  small 
that  it  may  well  be  dependent  upon  the  curvature  of  the  foetus. 

Internally  the  uterus  is  not  more  clearly  demarcated  from  the  vagina  than  externally.  Fol- 
lowing Daudt  I  take  the  first  of  the  transverse  folds  as  the  boundary.  Here  also  the  character 
of  the  surface  begins  to  change.  The  surface  of  the  fold  is  faintly  crenate  and  the  sulci  extend 
a  little  beyond  it,  but  soon  fade  out  and  the  mucosa  of  the  uterus  becomes  smooth.  Not  even 
with  the  binocular  could  I  detect  traces  of  the  longitudinal  folds  of  later  stages  either  in  the 
body  of  the  uterus  or  in  the  cornua.  From  the  point  of  union  of  the  cornua  a  septum  extends 
a  short  distance  into  the  body,  but  ends  before  its  constricted  middle  region  is  reached.  There 
was  no  asymmetry  internally  in  the  union  of  the  cornua,  such  as  Daudt  records  of  his  foetus. 

Ligamentum  latum. —  The  broad  ligament,  as  has  been  said,  is  concave  ventrally.  As  it 
nears  the  lateral  walls  of  the  abdomen  it  becomes  bent  upon  itself  dorsad  along  a  line  running 
from  the  arch  of  the  hypogastric  artery  to  the  proximal  convolution  of  the  oviduct.  Beyond 
this  line  the  ligament  is  directed  dorsad  as  well  as  laterad  gaining  attachment  to  the  parietes 


464  SCHULTE,  SEI  WHALE. 

approximately  at  the  transverse  level  of  the  body  of  the  uterus.  Adjacent  to  the  uterus  and 
cornu  as  far  laterad  as  the  line  just  mentioned  the  substance  of  the  ligamentum  latum  is  thick- 
ened and  almost  opaque,  beyond  the  line  thin  and  delicate.  Beauregard  and  Boulart :  describe 
a  mass  composed  of  fat  and  a  vascular  plexus  in  the  broad  ligament,  to  which  this  thickening 
as  to  the  structure  of  which  I  am  uncertain,  may  be  antecedent.  It  appeared  like  the  thick 
areolar  tissue  elsewhere  beneath  the  peritoneum,  in  which  a  beginning  deposit  of  fat  was  taking 
place.  The  injection  of  the  aorta  and  postcava  failed  to  extend  into  the  smaller  vessels  and  I 
was  unable  to  follow  any  into  this  region  of  the  broad  ligament.  The  attachment  of  the  body 
of  the  uterus  is  flush  with  its  ventral  surface.  As  a  result  of  this,  taken  together  with  the  thick- 
ening of  the  ligament,  the  outlines  of  the  body  and  also  of  the  proximal  portions  of  the  cornua 
are  obscured  in  ventral  view.  Towards  the  middle  of  the  cornua  small  furrows  appear  along 
their  concave  margins,  which  mark  them  off  from  the  ligament.  Dorsad  both  uterus  and  cornua 
project  strongly  and  the  cornua  are  further  demarcated  by  sulci.  It  is  as  though  these  structures 
in  being  moulded  ventrally  upon  the  smooth  bladder  had  lost  their  individual  relief,  while 
retaining  it  dorsally  where  less  intimately  in  contact  with  other  viscera.  At  the  sides  of  the 
bladder  the  ligament  follows  its  contour  entering  the  cleft  between  it  and  the  lateral  abdominal 
wall,  thence  returning  dorsad  to  its  attachment  with  the  resulting  formation  of  the  fold  before 
mentioned.  This  lateral  portion  is  triangular  in  shape  broadening  rostrad,  and  to  its  summit 
is  attached  the  oviduct. 

Two  accessory  folds,  in  addition  to  the  mesovarium,  are  present  in  the  domain  of  the  broad 
ligament,  one  on  its  ventral  the  other  on  its  dorsal  surface.  The  former  has  a  free  edge  extend- 
ing from  the  distal  portion  of  the  cornu,  2.5  mm.  from  its  junction  with  the  oviduct,  to  the  arch 
of  the  hypogastric  artery,  where  it  is  lost  in  the  parietal  peritoneum.  Within  it  is  a  delicate 
band  which  disappears  at  about  the  same  point,  thus  representing  the  round  ligament.  The 
second  dorsal  fold  is  larger.  It  extends  from  near  the  lower  pole  of  the  ovary  caudad  and  laterad, 
finally  sweeping  mesad  in  the  dorsal  paries  but  fading  out  before  it  reaches  the  aorta.  It  appears 
to  carry  the  ovarian  vessels. 

Vagina. —  The  vagina  begins  as  a  fusiform  dilatation  which  has  a  length  of  12  mm.  and 
is  then  continued  as  a  long  narrow  passage  to  the  vulva,  a  distance  of  19  mm.  This  distal  seg- 
ment is  in  contact  with  the  rectum,  to  which  it  presents  a  concave  dorsal  surface  as  far  as  the 
perineum  where  it  turns  ventrad  to  the  vestibule.  The  dilatation  is  marked  by  seven  very 
shallow  transverse  furrows,  which  correspond  to  transverse  folds  in  its  interior.  They  are 
deeper  and  farther  apart  at  its  middle,  fainter  and  nearer  together  at  its  ends.  Ventrally  only 
the  rostral  extremity  of  the  dilation  is  covered  by  peritoneum,  which  is  here  reflected  upon  the 
bladder.  Dorsally  the  whole  length  of  the  vagina  as  far  as  the  perineum  is  peritoneal,  a  narrow 
pouch  extending  between  it  and  the  rectum.  Ventrally  this  portion  is  in  relation  to  the  urethra, 
which  is  adherent  but  not  included  in  its  wall  and  the  two  are  surrounded  by  a  thick  fascia. 

The  interior  of  the  vagina,  after  the  removal  of  its  dorsal  wall,  shows  in  its  distal  segment 
a  mucosa  smooth  save  for  the  presence  of  delicate  longitudinal  folds,  which  become  obscure 
as  they  approach  the  dilated  portion.  Here  in  addition  to  the  seven  transverse  folds,  corre- 
sponding to  the  grooves  of  the  exterior  are  indications  of  the  formation  of  two  and  possibly  three 
more  folds  at  the  junction  with  the  distal  portion.  These  last  are  represented  by  rows  of  tuber- 
cular elevations  separated  by  shallow  sulci,  which  are  more  advanced  upon  the  ventral  wall, 

1  Beauregard  and  Boulart,  op.  cit. 


SCHULTE,  SEI  WHALE.  465 

where  the  first  forms  a  transverse  ridge  with  a  notched  margin,  like  the  fully  developed  folds 
farther  rostrad.  The  latter  are  largest  at  the  middle  of  the  dilatation  and  all  of  them  present 
the  characteristic  crenate  appearance.  Several  points  of  difference  emerge  in  the  comparison 
of  this  with  Daudt's  older  foetus  of  B.  musculus.  In  his  specimen  the  annular  folds  were  more 
numerous,  and  the  distal  smooth  portion  of  the  vagina  was  relatively  short.  This  makes  it 
highly  probable  that  the  region  of  the  folds  is  during  development  extended  caudad.  Of  this 
extension  by  formation  of  new  folds  there  is  further  evidence  in  the  rows  of  tubercles  referred 
to  above.  Nor  is  the  process  apparently  ended  in  Daudt's  foetus  of  121  cm.  For  here  in  addi- 
tion to  twelve  well  formed  rings,  were  a  few  of  little  prominence  and  not  completely  encircling 
the  vagina.  These  are  described  as  follows;  "Die  ersten  unteren  Ringe  sind  nur  durch  hoheres 
Hevorspringen  der  einzelnen  Faltchcn  veranlasst,  wahrend  bei  den  folgenden  auch  immer  der 
betreffende  Teil  der  Vaginalwandung  mit  in  das  Lumen  einspringt  und  so  ein  Glirtel  bildet, 
worliber  die  Falten  verlaufen."  It  would  appear  therefore  that  the  formation  of  the  annuli 
is  accomplished  by  the  appearance  of  tubercles,  which  at  first  involve  only  the  mucosa,  with  the 
secondary  formation  of  annular  folds,  upon  which  the  primary  elevations  appear  as  crenations. 
In  the  second  place  the  folds  in  Daudt's  foetus  fall  into  two  sets,  a  proximal  with  their  edges  turned 
towards  the  uterus,  a  distal  turning  their  margins  toward  the  vulva.  Between  the  two  sets 
is  an  especially  well  developed  fold,  with  a  T-shaped  cross  section.  The  equivalent  of  this  fold 
is  not  present  in  this  foetus.  The  fourth  and  fifth  folds  are  slightly  undermined  on  the  caudal 
aspects,  but  the  others  are  not  inclined  in  either  direction.  For  the  most  part  also  the  rings 
are  incomplete,  the  ridges  of  the  ventral  and  of  the  dorsal  walls  being  independent  and  inter- 
locking at  the  sides. 

ANGEIOLOGY. 
(Plate  LIII,  Fig.  2). 

Arteries. —  Only  the  aorta  and  the  proximal  portions  of  the  great  vessels  were  examined 
and  these  correspond  so  closely  to  Turner's  1  description  of  their  arrangement  in  B.  Sibaldii 
( =  musculus)  as  to  require  but  the  briefest  mention  here.  The  aorta  arching  over  the  root 
of  the  left  lung  reaches  the  vertebral  column  on  the  left  of  the  fifth  thoracic  vertebra,  and  arriving 
at  the  median  line  at  the  level  of  the  diaphragm  there  continues  to  the  haemal  canal  within  the 
arches  of  the  chevron  bones.  The  branches  of  the  arch  are  a  brachiocephalic,  left  common  caro- 
tid and  left  subclavian.  The  distance  between  the  first  and  second  is  very  considerable,  de- 
pendent no  doubt  upon  the  width  of  the  trachea.  The  left  subclavian  arises  from  the  dorsal 
aspect  of  the  arch.  It  then  ascends  to  the  rostral  margin  of  the  first  rib  and  passes  on  its  way  to 
the  flipper,  ventral  to  the  scalene.  In  its  arch  over  the  first  rib,  and  this  is  true  of  the  right  as  well, 
it  is  widely  separated  from  the  dome  of  the  pleura,  which  does  not  extend  beyond  the  caudal 
margin  of  this  rib.  On  each  side  an  artery  arches  over  the  dome  of  the  pleura,  and  produces 
a  slight  groove  on  the  apex  of  the  lung;  this  is  the  posterior  thoracic  of  Turner,  a  branch  of  the 
subclavian,  which  is  traceable  into  the  thoracic  rete.  The  descending  aorta  gives  off  the  twelve 
pairs  of  intercostals,  the  more  rostral  of  which  ascend  sharply  to  reach  their  respective  spaces. 

1  Turner,  W.     An  account  of  the  great  firmer  whale  (Balomoptera  Sibaldii),  stranded  at  Longnicldy.     Ft.  1.     The  soft  parts.     Trans. 
Ruy.  Soc.  Edin.,  Vol.  IV,  1872. 


466  SCHULTE,  SEI  WHALE. 

The  lumbar  segmental  arteries  are  peculiar  in  that  each  pair  arises  by  a  single  trunk  from  the 
aorta.  The  ventral  branches  in  the  abdomen  are  the  coeliac,  superior  mesenteric,  and  inferior 
mesenteric.  The  first  two  arise  in  close  proximity  immediately  below  the  diaphragm.  The 
coeliac  divides  into  a  hepatic  and  gastric,  from  which  latter  the  small  splenic  branch  is  derived. 
The  inferior  mesenteric  is  a  very  small  vessel  arising  but  a  short  distance  above  the  hypogastrics. 
Of  the  ventrolateral  series,  inferior  phrenic,  adrenals,  renals  and  sex  arteries  were  found.  Of 
the  latter  two  pairs  seemed  to  be  present.  The  inferior  were  large  and  arose  opposite  the 
inferior  mesenteric,  the  superior  were  large  and  situated  below  the  poles  of  the  kidneys.  Their 
course  carried  them  into  the  base  of  the  folds  on  the  dorsum  of  the  ligamentum  latum,  which 
ascend  to  the  ovaries.  The  hypogastrics  are  of  minute  size  and  arch  ventrad  to  the  sides  of  the 
bladder,  where  they  ascend  to  the  umbilicus,  being  invested  and  attached  to  the  bladder  by  a 
thick  sheath,  which  Daudt  finds  to  be  muscular.  From  the  arch  of  the  hypogastric  a  large 
trunk  is  given  off,  which  entering  the  foramen  in  the  rectus,  divided  into  a  large  ascending  branch 
to  the  rectus  muscle,  deep  epigastric,  and  a  descending  vessel  which  is  distributed  to  the  pelvic 
viscera  and  muscles. 

The  arteries  are  distinguished  by  the  enormous  thickness  of  their  wall.  In  the  ascending 
and  transverse  aorta,  the  lumen  is  reduced  to  a  mere  slit  between  two  longitudinal  cushion- 
like  ridges,  which  ascend  with  a  spiral  curve  from  the  region  above  the  sinuses  of  Valsalva.  Not 
until  it  receives  the  ductus  arteriorus  does  the  aorta  attain  a  circular  lumen.  The  sinuses  of 
Valsalva  are  deep  and  narrow.  They  are  not  visible  externally. 

The  pulmonary  artery  is  wide  and  short.  Its  wall,  though  very  thick,  is  less  than  that 
of  the  aorta,  and  its  circular  lumen  appears  more  capacious.  The  right  pulmonary  artery  has  a 
very  oblique  descending  course,  grooving  the  right  atrium  between  the  orifices  of  the  cavse. 
It  gives  off  its  apical  branch  as  it  crosses  the  primary  bronchus.  The  left  is  nearly  transverse 
and  much  shorter  than  the  right,  and  is  distinctly  diminished  in  diameter  after  giving  off  the 
ductus  arteriosus. 

Venous  system. —  The  systemic  venous  return  to  the  right  auricle  is  effected  by  a  postcava 
and  a  single  precava.  The  arrangement  of  the  great  veins  at  the  root  of  the  neck  and  in  the 
upper  mediastinum  is  of  the  common  asymmetrical  type  resulting  from  the  suppression  of  the 
left  precava  and  has  no  peculiarity  of  first  importance  save  in  the  reduction  and  modifica- 
tion of  the  azygos  veins.  The  great  vessels  here  considered  have  wide  lumina  and  walls  which 
are  thin  but  not  excessively  so;  the  internal  jugular  veins  are  especially  capacious  and  stand  in 
marked  contrast  to  the  small  subclavia.  These  trunks  unite  at  the  ventral  margin  of  the  scalene 
to  form  the  brachiocephalica,  which  are  appreciably  less  in  cross-section  than  the  sum  of  the 
cross-sections  of  the  confluent  vessels.  The  same  is  true  in  higher  degree  of  the  precava  as  com- 
pared with  the  two  brachiocephalicse.  The  left  of  these  veins  has  a  very  oblique  course  within 
the  thorax  resting  upon  the  thyroid  gland  and  the  arch  of  the  aorta  and  having  the  thymi  on  its 
caudal  aspect,  from  the  interval  between  which  it  receives  the  large  thymic  vein.  The  right 
brachiocephalica  runs  directly  caudad.  At  the  level  of  the  dome  of  the  pleura  a  large  vessel 
joins  the  brachiocephalic  of  each  side.  This  accompanies  the  posterior  thoracic  artery,  drain- 
ing its  plexus,  but  in  addition  by  a  large  spinal  tap  affords  an  outlet  to  the  intravertebral  plexus. 
The  precava  is  very  short  and  immediately  enters  the  pericardium,  within  which  it  turns  ventrad 
and  slightly  to  the  left.  The  angle  its  ventral  wall  makes  with  the  auricle  is  deepened  to  a 
narrow  cleft,  which  marks  the  rostral  extremity  of  the  sulcus  terminalis. 


SCHULTE,  SEI  WHALE.  467 

The  azygos  system  is  rudimentary.  It  is  described  as  absent  in  Phoccena  by  v.  Baer.1 
The  azygos  major  in  this  foetus  is  absent;  no  vessel  arches  over  the  root  of  either  lung,  and  the 
absence  of  this  vein  on  the  right  side  may  well  be  associated  with  the  presence  and  large  size  of 
the  tracheal  bronchus.  Three  lines  of  drainage  for  the  intercostal  veins  are  however  present 
on  each  side,  in  addition  to  the  intraspinous  trunks,  with  which  the  intercostals  communicate 
through  the  intervertebral  foramina.  These  are  the  internal  mammary  and  lateral  internal 
mammary  of  the  subclavian,  and  the  superior  intercostal  of  the  posterior  thoracic  vein.  On 
the  right  side  of  the  bodies  of  the  thoracic  vertebrae,  dorsal  in  position  to  the  ganglionic  cord, 
there  is  a  small  zigzag  vessel,  which  rostrad  is  continued  into  the  superior  intercostal  vein. 
Laterad  it  receives  the  intercostals  of  the  right  side,  mesad  those  of  the  left,  which  cross  the 
vertebral  centra  at  their  middle  to  reach  it.  In  this  way  a  portion  of  the  return  flow  from  the 
left  intercostal  spaces  below  the  fifth  reaches  the  right  side.  The  upper  left  spaces  drain  into  the 
superior  intercostal  of  the  left  side.  In  the  small  longitudinal  vessel  of  the  right  side  must  be 
seen  the  representative  of  the  hemi-azygos  major,  but  in  a  reduced  condition,  for  the  physio- 
logically important  drainage  seems  to  be  into  the  vertebral  canal. 

Through  the  intraspinous  vessels  a  communication  is  established  between  the  precaval 
and  postcaval  veins,  for  the  latter  has  large  spinal  taps,  especially  in  the  subhepatic  segment. 
These  intraspinous  vessels  are  placed  ventral  to  the  nerve  roots,  against  the  bodies  of  the  ver- 
tebrae, in  the  space  between  the  theca  medullse  spinalis  and  the  periosteum  and  posterior  common 
ligament  of  the  vertebrae;  beyond  these  points  they  are  continued  as  smaller  vessels,  rostrad 
communicating  through  the  foramen  magnum  with  the  occipital  sinuses.  Through  the  inter- 
vertebral  foramina  they  communicate  with  the  segmental  veins.  On  the  centra  they  are  con- 
nected by  cross  branches,  which  receive  tributaries  from  the  centres  of  ossification.  In  spite 
of  these  numerous  cross-anastomoses  these  intraspinous  trunks  are  not  plexiform,  but  are  well 
formed  veins  of  sinuous  course,  in  size  exceeding  that  of  the  postcava  distad  of  the  renal  vessels, 
from  which  it  is  evident  that  physiologically  they  form  an  important  element  of  the  venous 
system.  From  their  connections  it  is  evident  that  they  may  serve  as  an  equilibrating  anastomo- 
sis between  the  precaval  and  postcaval  systems.  With  the  former  they  communicate  by  means 
of  the  large  tap  between  the  third  and  fourth  thoracic  vertebra  into  the  posterior  thoracic  vein. 
In  the  lumbar  region  they  communicate  with  the  postcava  by  a  large  communication  with  its 
subhepatic  segment,  and  by  a  series  of  smaller  anastomoses  between  the  lumbar  veins  and  the 
supracardinal  cross-anastomoses  between  the  postcavse  on  the  dorsum  of  the  aorta.  It  would 
seem  probable  that  the  great  development  of  this  system  is  associated  with  the  suspension  of 
thoracic  respiration  for  considerable  periods,  and  the  less  favorable  condition  of  the  venous 
return  depending  upon  the  cessation  of  thoracic  aspiration.  Assuming  this  relative  impediment, 
the  system  may  operate  to  prevent  venous  congestion  of  the  cerebrum  by  affording  an  outlet 
from  the  precaval  to  the  postcaval  drainage  area,  in  which  latter  engorgement  might  be  better 
tolerated  by  virtue  of  the  great  distensibility  of  the  abdominal  veins,  which  is  usual  in  mammals. 
There  is  thus  a  means  of  maintaining  equilibrium  between  the  precaval  and  postcaval  systems, 
in  accordance  to  the  demands  of  which  the  current  in  the  vertebral  plexus  may  be  reversed  and 
drain  at  need  into  either  cava.  Of  such  collateral  anastomoses  between  the  caval  districts  there 
are  in  general  among  vertebrates  three  longitudinal  paths,  the  spinal,  the  lateral  abdominal,  and 
the  azygos,  of  which  the  first  two  are  characteristic  of  reptiles,  the  last  of  mammals. 


1  Baer,  C.  E.  von.     Uber  die  Gefassysteme  des  Braunfisches.     Nova  acta  physico-medica,  T.  70,  1835. 


468  SCHULTE,  SEI  WHALE. 

The  azygos  depends  developmentally  upon  the  appearance  in  mammalia  of  the  supracardi- 
nal  veins,  a  neomorphic  longitudinal  system,  intermediate  in  position  between  the  postcardinals 
and  the  vessels  of  the  spinal  canal,  with  both  of  which  it  communicates  at  frequent  intervals. 
The  fact  that  the  azygos  as  well  as  a  large  portion  of  the  postcava,  is  of  supracardinal  origin 
offers  a  satisfactory  explanation  of  the  differences  obtaining  in  these  systems  as  between  mam- 
mals and  reptiles,  in  which  latter  the  supracardinals  are  not  developed,  and  in  the  second  line 
affords  a  standpoint  for  the  interpretation  of  the  variations  in  the  azygos  and  spinal  collateral 
circulation  within  the  class  mammalia.  As  regards  the  latter,  communications  between  the  post- 
cava and  the  spinal  plexus  are  so  universally  found  when  looked  for,  though  not  always  of  large 
size,  that  their  omission  in  the  description  of  a  specific  type  of  circulation,  is  far  from  being 
evidence  of  their  absence.  In  my  judgment  they  are  to  be  looked  upon  as  a  general,  though  not 
always  conspicuous,  feature  of  the  mammalian  plan  of  circulation.  Their  common  rostral  drain- 
age is  by  way  of  the  vertebral  veins.  Large  thoracic  taps  are  infrequent,  but  an  approach  to 
the  condition  present  in  the  Cetacea  exists  in  the  usual  large  spinal  tap  of  the  artiodactyl  cer- 
vico-costal  vein,  which  in  our  experience  is  normally  present.  In  these  communications  we  have 
a  persistence  of  a  part  of  the  far  greater  system  of  anastomoses  of  the  embryo  mammal,  as  well 
as  in  its  definitive  pattern  a  retention  of  the  reptilian  type.  With  the  appearance  of  the  azy- 
gos —  the  thoracic  supracardinal  —  and  the  development  of  its  prevertebral  anastomoses  with 
the  postcava,  a  collateral  equilibratory  line  is  established,  which  is  evidently  favorably  placed 
with  regard  to  the  mechanics  of  circulation  in  most  mammals,  for  its  presence  as  a  rule  is  associ- 
ated with  a  reduction,  not  suppression,  of  the  spinal  taps  and  of  the  longitudinal  anastomosis  of 
the  abdominal  wall.  As  a  rare  variant  it  may  even  supplant  the  suprahepatic  postcava  which 
then  discharges  by  way  of  the  azygos  major  into  the  precaval  trunk.1  In  the  case  of  forms  such 
as  the  one  under  consideration  we  are  of  course  in  doubt  from  lack  of  knowledge  of  the  embryo, 
whether  we  are  dealing  with  a  rudimentary  supracardinal  system,  or  whether  the  supracardinals 
have  here  developed  and  undergone  a  subsequent  reduction  in  the  embryo.  Their  evident  role 
in  the  formation  of  the  postcava  favors  the  latter  supposition.  We  have  here  an  illustration  of 
the  difficulties  inherent  in  the  comparison  of  adult  types  of  the  venous  system,  when  their  develop- 
ment is  not  known,  for  in  view  of  the  multiplicity  of  the  embryonic  vessels,  almost  any  variant 
is  easily  explainable  as  a  retention  of  some  portion  of  the  primitive  network  which  is  usually 
lost,  and  convergence  may  be  achieved  by  differing  developmental  processes. 

The  postcava  has  but  a  minimal  prehapetic  segment  on  account  of  the  dorso-ventral  orien- 
tation of  the  heart,  its  lack  of  rotation,  and  the  close  adherence  of  the  pericardium  to  the  dia- 
phragm. Its  hepatic  segment  lies  at  the  bottom  of  a  deep  caval  fissure,  the  apposition  of  the 
walls  of  which  conceals  it  from  view.  It  receives  just  before  its  emergence  proximad  a  large  right 
and  left  hepatic  vein,  and  separately  on  rather  a  more  dorsal  plane  the  ductus  venosus.  It 
leaves  the  liver  caudad  beside  a  very  rudimentary  caval  lobe,  and  descends  with  an  inclination 
to  the  left  to  the  level  of  the  renal  veins.  In  this  portion  of  its  course  it  is  entirely  retroperitoneal, 
having  the  portal  vein  and  sagittal  portion  of  the  pancreas  ventral,  and  both  adherent  to  it.  In 
this  portion  of  its  course  it  receives  the  right  adrenal  vein  and  communicates  by  a  large  dorsal 
branch  with  the  vessels  of  the  spinal  cord.  This  anastomosis  permits  of  the  blood  conveyed 
. — • . — _ — * . 

1  Cf.  McClure,  C.  F.  W.  A  contribution  to  the  anatomy  and  development  of  the  venous  system  of  Didelphys  marsupialis  (L.). 
Pt.  2.  Development.  Am.  Jour.  Anat.,  Vol.  5,  1908.  McCallum,  W.  G.  Anomaly  of  the  inferior  vena  cava  with  thrombosis.  N.  Y. 
Path.  Soc.,  Vol.  XII,  1912. 


SCHULTE,  SEI  WHALE.  469 

by  the  distal  postcava  finding  its  way  to  the  heart  by  two  paths,  that  of  the  postcava  itself, 
or  through  the  intraspinal  veins  to  the  posterior  thoracic  veins  and  so  through  the  brachio- 
cephalicse  to  the  precava.  In  consequence  the  subhepatic  cava  may  be  reduced  in  size,  in 
this  foetus  to  but  a  very  moderate  degree,  and  this  reduction  has  been  cited  by  Beddard  '  as  evi- 
dence of  edentate  affinities  on  the  part  of  the  Cetacea.  Such  cavo-spinal  communications  are 
of  wide  distribution  among  the  mammalia  and  are  a  normal  feature  of  the  more  extensive  venous 
system  of  the  embryo.  It  is  therefore  difficult  to  evaluate  their  taxonomic  importance,  even 
when  highly  developed,  and  in  view  of  the  variability  of  the  venous  system  their  character  ought 
to  be  determined  by  numerous  observations  upon  the  forms  compared.  Morphologically  they 
must  be  regarded  as  phyletically  primitive  characters  —  for  the  intraspinal  path  is  highly  organ- 
ized and  of  large  size  in  reptiles  —  and  not  as  specializations,  except  to  the  degree  that  the 
selection  and  hypertrophy  of  a  widely  distributed  character,  if  proved  to  be  constant  and  uniform 
in  a  species  or  order,  may  have  this  value.  A  venous  peculiarity  is  a  criterion  which  must  be 
used  with  extreme  caution,  and  even  when  of  considerable  magnitude  is  not  always  a  proof  of 
genetic  relationship.  In  Marsupials  and  in  Tragulus  the  postcava  has  in  general  the  preaortic 
position,  yet  in  some  Marsupials,  departures  from  this  type  are  recorded.  In  Petauroides 
volans  the  postcava  lies  to  the  right  and  dorsal  to  the  aorta  (Hochstetter,  Schulte) ;  in  Pseudo- 
chirus  it  sometimes  does  so,  sometimes  is  preaortic;  in  Didelphys  marsupialis  it  may  as 
a  variant  have  a  left  dorso-latreal  relation  to  the  aorta  (McClure). 

The  region  of  the  subcardinal  anastomosis  has  here  the  form  of  a  confluence  of  the  two 
renal  veins  with  the  postcava.  The  renal  veins  emerge  from  the  ventral  surfaces  of  the  kidneys 
near  their  upper  poles  and  ascend  in  a  curved  course  to  join  the  cava,  the  distal  trunk  of  which 
but  little  exceeds  either  of  the  renal  veins  in  size.  The  left  vein  enters  at  a  slightly  lower  level, 
turning  its  proximal  segment  almost  into  the  line  with  the  cava  as  it  does  so.  Here  the  veins 
are  demarcated  for  a  short  distance  by  a  sulcus  which  prolongs  their  angle  of  union.  The 
left  renal  vein  receives  the  left  adrenal  and  the  left  phrenic  veins  as  tributaries.  The  right 
is  joined  by  the  phrenic  of  its  side. 

The  cava  continues  distad  only  a  short  distance  as  a  single  trunk.  In  the  greater  part  of 
the  lumbar  region  it  is  double,  the  vein  of  the  right  side  slightly  preponderating  in  size.  The 
junction  of  the  left  postcava  with  the  right  is  effected  dorsal  to  the  aorta  by  numerous  oblique 
branches  of  anastomosis.  This  condition  is  found  in  Monotremes,  a  resemblance  which  may 
serve  to  illuminate  that  subsisting  between  Cetacea  and  Edentates  (Xenarthra)  in  the  cavo- 
vertebral  anastomosis.  These  communications  ascend  obliquely  from  left  to  right,  and  are 
of  considerable  relative  size.  In  the  region  rostrad  of  the  hypogastric  arteries  nine  were 
present.  By  them,  as  may  be  inferred  from  their  direction,  blood  is  conveyed  from  the  left  to  the 
right  postcava.  The  left  vessel  is  thus  depleted  and  the  last  of  the  oblique  vessels  connects 
its  termination  with  the  right  cava.  Between  these  supracardinal  anastomotic  vessels,  the 
dorsal  segmental  branches  of  the  aorta  pass  to  their  distribution.  The  whole  arrangement, 
apart  from  the  size  of  the  vessels,  is  very  similar  to  that  of  Ornithorhynchus.'1 

1  Beddard,  F.  E.     Mammalia.     Cambridge  Nat.  Hist.,  Vol.  X,  1902,  p.  120.     Cf.  Gregory,  \V.  K.     Orders  of  Mammals.     Bull. 
Am.  Nat.  Hist.,  Vol.  XXVII,  1910,  p.  414. 

2  Hochstetter,  F.     Beitrage  zur  Entwickelungsgeschichte  des  Venensystems  der  Amnioten.     3.  Sauger.  Morph.  Jahrb.,  Bd.  XX, 
1893.    Schulte,  H.  von  W.     The  range  of  variations  in  Monotremes  and  Australian  Masupials.     Proc.  Am.  Ass.  Anat.,  21st  Sess.     Anat. 
Rec.,  Vol.  1,  1907.     Schulte,  H.  von  W.,  and  Tilney,  F.     A  note  on  the  organization  of  the  venous  return  with  especial  reference  to 
the  iliac  veins.     Anat.  Rec.,  Vol.  3,  1909. 


470  SCHULTE,  SEI  WHALE. 

At  the  level  of  the  hypogastric  artery  the  postcava' receives  on  each  side  a  large  iliac  vein, 
beyond  which  they  are  continued  into  the  caudal  veins  which  soon  become  plexiform.  While 
draining  into  both  postcavse  the  connection  is  distinctly  larger  on  the  right  side.  Between  the 
origins  of  the  hypogastric  arteries  a  small  ventral  anastomotic  branch  ascends  from  the  left  iliac 
to  the  right  postcava.  This  is  connected  on  each  side  by  a  slender  vessel  with  both  caudal 
veins.  In  anastomoses  placed  ventral  to  the  arteries  we  have  the  retention  of  an  embryonic 
condition  common  to  Monotremes,  Marsupials  and  Placentals,  which  is  highly  developed  in  the 
first,  a  frequent  variant  in  the  second,  and  is  regularly  replaced  by  a  dorsal  anastomosis  in  the 
adults  of  the  third.  The  passage  of  the  anastomosis  dorsal  to  the  aorta  at  this  point  is  also 
common  to  the  three  subclasses,  and  is  frequently  of  high  development  among  the  Marsupials, 
although  they  show  much  individual  variation  in  this  arrangement. 

Of  the  several  axial  embryonic  venous  channels  which  may  form  the  postrenal  segment 
of  the  postcava,  it  is  practically  certain  that  it  is  the  supracardinal  of  Huntington  and  McClure 
which  has  here  persisted,  for  the  ureter  is  free  of  the  postcava  and  does  not  twist  around  it  as 
is  the  case  with  the  retention  of  the  postcardinal,  while  the  possibility  of  the  existence  and  reten- 
tion of  the  cardinal  collateral  of  McClure  seems  excluded  by  the  lateral  position  of  the  post- 
cava beside  the  aorta.  The  existence  of  this  vessel,  in  the  present  state  of  our  knowledge,  can 
hardly  be  asserted  except  of  Marsupials  and  Tragulus,  and  its  retention  gives  rise  to  a  cava  of 
preaortic  position.  We  may  then  recognize  in  the  postcaval  system  of  this  fcetus  distad  of  the 
liver,  a  subcardinal  portion  comprising  the  subhepatic  trunk  and  the  debouchment  of  the  renal 
veins,  and  a  supracardinal  represented  by  the  double  veins  and  the  anastomosis  dorsal  to  the 
aorta. 

In  the  course  of  the  postcava?  numerous  small  tributaries  enter  laterally  from  the  plexus 
upon  the  hypaxial  muscle  and  from  the  substance  of  the  muscle  itself.  The  sex  veins  failed  to 
be  injected  and  I  was  unable  to  recognize  them  with  any  certainty.  A  rather  large  vein  near 
the  middle  of  the  cava  was  directed  laterad  towards  the  ovary,  but  I  could  not  determine  its 
drainage  area. 

The  postcava  of  this  fcetus  differs  in  one  respect  from  that  described  and  figured  by  Daudt l 
in  B.  musculus.  In  this  specimen  the  left  postcava  was  carried  up  to  the  renal  level  and  its 
contents  gained  access  to  the  single  subhepatic  cava  by  means  of  the  subcardinal  anastomosis, 
which  is  the  typical  placental  arrangement  in  cases  of  double  postcava.  In  his  specimen  dorsal 
anastomoses  are  hot  recorded  and  the  cavo-spinal  anastomosis  is  represented  by  several  vessels. 


CERVICO-BRACHIAL  PLEXUS. 

Cervical  plexus. —  The  ventral  divisions  of  the  first  four  cervical  nerves  conform  to  the 
usual  mammalian  type  as  far  as  their  muscular  branches  and  communications  are  concerned; 
cutaneous  branches  I  was  unable  to  examine.  The  first  and  second  communicate  ventrad  of  the 
transverse  process  of  the  atlas.  From  this  loop  the  decendens  cervicalis  is  given  off  to  the  hypo- 
glossal.  The  communicans  arising  from  the  second  and  third,  crosses  the  carotid  and  joins  the 
decendens  shortly  after  it  parts  company  with  the  hypoglossal.  Thus  a  very  short  anser  is 
formed,  from  which  a  trunk  descends  in  the  carotid  sheath  and  resolves  itself  into  branches  for 


Daudt,  W.,  op.  cit.,  pi.  vii,  fig.  7. 


SCHULTE,  SEI  WHALE. 


471 


the  infrahyoid  muscles.  From  the  second  nerve  a  branch  is  given  to  the  sterno-mastoid  which 
anastomoses  on  its  deep  surface  with  the  spinal  accessory,  and  a  large  branch  from  the  third 
behaves  in  a  similar  manner  with  reference  to  the  tra- 
pezius  and  masto-humeralis.  These  branches  of  the 
second  and  third  nerves  emerge  from  a  cleft  in  the 
scalene,  in  its  upper  third  and  on  its  ventrolateral  as- 
pect, not  in  line  with  the  more  ventral  cleft  in  the  caudal 
third  of  the  muscle,  which  gives  passage  to  the  brachial 
plexus.  The  phrenic  nerve  emerges  from  the  ventro- 
mesal  aspect  of  the  scalene,  opposite  the  middle  of  the 
cleft  for  the  plexus.  It  is  derived  mainly  from  the 
fourth  nerve  but  on  the  right  was  joined  by  a  small 
branch  of  the  fifth.  These  first  four  cervical  nerves  join 
in  the  supply  of  the  scalene  and  hypaxial  muscles  of  the 
neck.  The  suboccipital  nerve  gives  branches  to  the 
rectus  capitis  lateralis  and  to  the  obliquus.  All  com- 
municate with  the  large  superior  cervical  ganglion  of 
the  sympathetic. 

Brachial  plexus. —  The  ventral  divisions  of  the 
nerves  entering  into  this  plexus  increase  in  size  caudad 
to  the  eighth  cervical,  which  is  at  least  ten  times  the 
size  of  the  fifth;  the  first  thoracic  is  of  large  size  but 
distinctly  less  than  that  of  the  eighth  cervical.  In  the 
scalene  cleft  the  usual  primary  trunks  are  formed,  the 
upper  by  the  union  of  the  fifth  and  sixth,  the  lower  by 
that  of  the  eighth  cervical  and  the  first  thoracic,  while 
the  seventh  cervical  remains  single  forming  a  middle 
trunk.  Before  emergence  the  upper  and  middle  trunks 
unite  to  form  a  short  upper  cord,  which  promptly  resolves  itself  into  branches  of  distribution 
and  anastomosis.  Of  the  latter  one  joins  the  lateral  cutaneous  branch  of  the  lower  trunk,  its 
fibres  being  largely  but  not  entirely  continued  into  the  internal  anterior  thoracic  nerves  to  the 
pectoralis.  The  other  anastomotic  branch  joins  with  a  similar  branch  of  the  lower  trunk  in  a 
loop,  from  the  apex  of  which  is  given  off  the  combined  circumflex  and  musculo-spiral  trunk.  It 
is  therefore  representative  of  the  posterior  cord  of  more  usual  plexus  types,  the  chief  peculiarity 
being  incident  to  the  complete  union  of  the  upper  and  middle  primitive  trunks  prior  to  the 
origin  of  the  so-called  posterior  branches,  so  that  these  are  represented  by  a  common  branch, 
which  in  addition  to  the  usual  components  carries  fibres  destined  for  the  musculo-cutaneous 
nerve.  There  is  further  no  separate  median  nerve. 

The  suprascapular  nerve  is  given  off  from  the  short  cord  resulting  from  the  union  of  the 
upper  and  middle  trunks.  It  enters  the  interval  between  subscapularis  and  supraspinatus, 
the  latter  of  which  it  supplies,  and  passing  between  the  supraspinatus  and  the  border  of  the 
scapula  crosses  the  bone  dorsally  to  reach  the  infraspinatus. 

The  subscapular  nerves  are  three  in  number.  They  are  derived  from  the  lateral  branch 
of  communication  of  the  upper  cord;  the  third  is  the  largest  and  ends  in  the  teres  major.  The 


Fig.  6.  Schema  of  brachial  plexus.  1,  Supra- 
scapular  nerve.  2,  Subscapular  nerves.  3,  Musculo- 
cutanens  nerve.  4,  Musculo-spiral  nerve.  5,  Circum- 
flex nerve.  6,  Ulnar  nerve.  7,  Internal  cutaneous 
nerve.  8,  Nerve  of  the  latissimus  dorsi.  9,  Nerve  of 
the  panniculus  carnosus.  10,  Anterior  thoracic  nerves. 


472  SCHULTE,  SEI  WHALE. 

nerve  to  the  latissimus  is  derived  from  the  beginning  of  the  circumflex-musculo-spiral  trunk. 
If  it  gave  any  branches  to  the  subscapularis  I  failed  to  find  them. 

The  musculo-cutaneous  nerve  arises  from  the  lateral  branch  of  anastomosis  close  to  its 
union  with  the  branch  of  the  lower  trunk.  It  crosses  the  humerus  obliquely  passing  beneath 
the  bicipital  ligaments.  At  the  elbow  it  gives  off  a  branch  to  the  flexor  carpi  radialis  and  the 
radial  side  of  the  flexor  communis  digitorum.  Its  cutaneous  filaments  were  distributed  along 
the  preaxial  margin  of  the  flipper.  In  its  muscular  supply  it  is  seen  to  carry  fibres  which  are 
usually  included  in  the  median.  The  nerve  to  the  coraco-brachialis  was  given  off  from  its  upper 
portion  near  its  origin. 

The  musculo-spiral  and  circumflex  nerves  are  derived  from  a  common  trunk  which  con- 
stitutes the  posterior  cord  of  the  plexus.  This  lies  upon  the  subscapularis  as  far  as  its  caudal 
border,  where  it"  divides.  The  circumflex  turns  dorsad  in  the  interval  between  the  teres  major, 
subscapularis  and  humerus  to  reach  the  dorsum  of  the  scapula,  where  it  supplies  the  deltoid 
and  subdeltoideus.  The  musculo-spiral  passes  in  its  usual  position  behind  the  humerus  to  the 
preaxial  border  of  the  flipper.  It  supplies  the  triceps  and  the  extensor  digitorum. 

The  ulnar  nerve  arises  from  the  lower  cord  by  a  short  trunk  in  common  with  the  communi- 
cating branch  and  the  internal  cutaneous.  It  passes  distal  to  the  interval  between  the  flexor 
carpi  ulnaris  and  the  flexor  digitorum  to  both  of  which  it  gives  branches.  At  the  wrist  it  divides 
into  branches  which  pass  down  the  spaces  between  the  digits  and  along  the  ulnar  side  of  the 
fifth  digit.  The  internal  cutaneous  nerve  was  smaller.  I  succeeded  in  following  it  only  to  the 
region  of  the  olecranon. 

'  The  internal  anterior  thoracic  nerves  are  derived  from  the  lower  trunk  immediately  oppo- 
site the  point  where  it  receives  the  mesal  communicating  branch.  Some  of  the  fibres  from  this 
source  form  a  ridge  upon  the  trunk  and  are  directly  traceable  to  the  thoracic  nerves,  which  are 
largely  yet  not  wholly  the  continuation  of  these  fibres.  They  enter  the  sternocostal  portion 
of  the  pectoralis  on  its  deep  surface. 

The  pannicular  nerve,  lateral  cutaneous  of  English  authors,  is  the  largest  branch  of  the 
brachial  plexus  and  forms  the  continuation  of  its  lower  trunk  after  it  is  joined  by  the  mesal  com- 
municating branch.  It  is  directed  caudad  under  cover  of  the  pectoralis,  to  the  abdominal 
portion  of  which  it  distributes  small  branches,  and  continues  caudad  beneath  the  lateral  raphe, 
breaking  up  beside  the  vulva  into  large  branches  for  the  ventral  and  dorsal  divisions  of  the 
panniculus,  to|both  of  which  throughout  its  course  it  supplies  numerous  smaller  twigs.  At 
the  caudal  border  of  the  axilla  it  gives  off  a  large  branch  on  its  mesal  aspect,  which  dividing  in 
two  turns  round  the  latissimus  dorsi  and  is  distributed  to  the  dorsal  panniculus  in  the  scapular 
and  postscapular  regions. 

The  lower  four  cervical  nerves  and  the  first  thoracic  communicate  with  a  stellate  ganglion. 
It  is  situated  'upon  the  lateral  surface  of  the  rectus  anticus,  in  the  triangular  space  between 
that  muscle  and  the  scalenus  in  close  proximity  to  the  vertebral  vessels,  which  are  lateral  to  it. 
It  measures  6  mm.  by  4  mm.  x  1  mm.  Its  branches  of  distribution  upon  the  subclavian  artery 
and  the  arteries  arising  from  it  are  conspicuous  for  their  large  size. 


SCHULTE,  SEI  WHALE.  473 

THE  SKELETON. 
(Plates  LIV-LVII). 

SKULL. 

The  cranium  is  broadly  oval  with  a  high  arched  vertex.  The  rostrum,  though  large,  is  far 
from  approaching  its  adult  proportions,  and  the  frontal  and  squamosal  project  as  yet  but  moder- 
ately from  the  sides  of  the  brain-case.  As  a  result  of  these  several  factors,  together  with  the 
decurvate  tip  of  the  rostrum  and  the  caudal  position  of  the  temporo-maxillary  articulation, 
the  skull  has  a  strikingly  avian  appearance.  The  definitive  elements  in  detail  are  well  defined, 
and,  proportions  aside,  have  the  same  general  arrangements  and  connections  as  in  the  adult. 
The  most  important  exception  to  this  statement  is  the  all  but  complete  exposure  of  the  inter- 
parietal,  with  the  concomitant  wide  interval  between  the  frontal  and  supra-occipital.  There  is 
a  broad  fontanelle  at  the  rostral  margin  and  sides  of  the  interparietal.  On  the  base,  the  audi- 
tory bullse  are  conspicuous  for  their  relatively  enormous  size. 

The  following  calliper  measurements  are  intended  to  afford  some  basis  for  estimating  the 
differential  growth,  by  which  eventually  the  skull  attains  its  adult  proportions: 

Table  V.     Measurements  of  skull  of  foetus  of  Balcenoptera  borealis. 

mm. 

Length  from  tip  of  septal  cartilage  to  condyle 100 . 

Breadth  between  rostral  angles  of  orbital  processes  of  frontals 48 . 

Breadth  between  caudal  angles  of  orbital  processes  of  frontals 61 . 

Breadth  between  rostral  extremities  of  zygomatic  processes  of  squamosals 61 . 

Breadth  between  extremities  of  postglenoid  processes  of  squamosals 52 . 5 

Breadth  between  parietal  eminences 42 . 5 

Breadth  between  extremities  of  exoccipitals 39 . 5 

Depth  from  rostral  margin  of  supra-occipital  to  hamular  process 47 . 

Length  of  rostrum 53 . 

Greatest  breadth  of  rostrum 38 . 

Length  of  maxilla,  from  frontal  border 48 . 

Breadth  of  same  at  orbital  process 25 . 5 

Breadth  of  same  at  base  of  rostrum 21 . 

Length  of  premaxilla 55 . 5 

Greatest  breadth  of  same,  at  middle  of  rostrum 5.5 

Length  of  nasal  in  median  line 5.5 

Breadth  of  same  at  rostral  end 3.5 

Distance  from  rostral  end  of  nasal  to  rostral  border  of  supra-occipital ".  .  42 . 

Distance  from  rostral  end  of  nasal  to  rostral  border  of  interparietal 23 . 

Sagittal  length  of  orbit 21 . 

Greatest  dorso-ventral  diameter  of  same 18. 

Depth  from  base  to  apex 

Length  of  hard  palate 67 . 

Greatest  length  of  palate  bone ' 18 . 5 

Length  of  fibrous  bulk 21 .5 

Breadth  of  fibrous  bulla 16 . 

Length  of  hamular  process 9-5 

In  the  description  which  follows  I  have  concerned  myself  chiefly  with  the  general  archi- 
tecture of  the  skull,  omitting  details  regarding  the  individual  elements,  except  in  a  few  instances 


474  SCHULTE,  SEI  WHALE. 

where  they  show  important  departures  from  adult  conditions.  For  the  study  of  the  cartilaginous 
structures  deBurlet's  fine  studies  of  the  chondrocranium  have  been  of  the  greatest  assistance, 
and  I  am  also  under  obligations  to  Prof.  W.  K.  Gregory,  who  has  allowed  me  to  consult  him  upon 
many  points  of  difficulty. 

Norma  occipitalis.  As  a  whole  this  surface  narrows  towards  the  vertex  from  the  post- 
glenoid  processes;  this  outline  is  however  broken  at  the  sides  by  the  projection  of  the  zygomatic 
processes  of  the  squamosal  and,  farther  dorsad,  by  the  rounded  convexities  of  the  parietals. 
The  foramen  magnum  is  enclosed  between  the  exoccipitals  and  basioccipital  which  are  represented 
by  a  continuous  cartilage  in  which  three  ossification  centres  have  appeared.  Those  of  the 
ex-occipitals  are  quadrangular  and  occupy  the  greater  part  of  the  intervals  between  the  paroc- 
cipital  processes  and  the  condyles.  The  third  is  much  smaller  and  situated  in  the  basioccipital. 
The  foramen  magnum  is  oval  with  its  long  axis  dorso ventral;  it  narrows  ventrally  between 
the  condyles  and  in  its  dorsal  contour  a  similar  but  slighter  narrowing  is  present.  Vertically 
it  measures  10  mm.,  transversely  8  mm.  The  plane  of  its  orifice  looks  caudad  and  to  a  slight 
degree  dorsad.  The  condyles  are  born  on  very  short  condylar  processes.  They  are  almost 
flat  transversely,  moderately  convex  dorsoventrad.  The  lateral  margins  are  strongly  convex, 
almost  angulate  at  their  region  of  greatest  convexity  where  they  pass  on  to  the  base  of  the 
skull.  The  mesal  borders  are  nearly  straight  except  towards  the  extremities  where  they  arch 
laterad.  These  straight  mesal  margins  converge  until  they  are  only  1.5  mm.  apart.  Between 
them  and  the  margin  of  the  foramen  magnum  is  a  small  area  serving  for  the  attachment  of 
ligaments  and  showing  near  its  apex  the  section  of  the  notocord.  The  condyles  measure  13  mm. 
in  length,  7  mm.  at  their  greatest  breadth.  The  distance  between  their  caudal  extremities  is  10 
mm.,  between  their  ventral  4  mm.  Lateral  to  the  condyle  is  a  narrow  gutter  in  which  is  inserted 
the  combined  scalenus  and  rectus  anticus;  beyond  this  the  cartilage  rises  in  blunt  elevations. 
Of  these  the  most  ventral  is  the  paroccipital  (paramastoid)  process,  which  gives  attachment 
to  the  rectus  capitis  lateralis,  and  is  placed  dorsolateral  to  the  jugular  foramen.  It  is  separated 
by  a  depression  from  a  more  prominent  vertical  ridge,  which  gives  attachment  to  an  atlanto- 
occipital  muscle,  the  superior  oblique.  Dorsal  to  this,  again  separated  by  a  concavity,  is  a  broad 
convexity  serving  for  the  attachment  of  the  longissimus  dorsi  and  of  the  muscle  which  I  have 
described  as  the  trachelo-occipitalis. 

The  supra-occipital  is  excluded  from  the  foramen  magnum  by  the  exoccipitals.  It  is  ob- 
scurely pentagonal  in  form,  the  rostral  and  lateral  margins  tending  to  fall  into  an  irregular 
arch.  In  its  whole  extent  it  affords  attachment  to  the  semispinales  muscles.  Rostrad  its  margin 
slightly  overrides  the  interparietal  and  here  gives  origin  to  the  occipitalis.  Near  its  lateral 
margin  it  is  in  contact  with  the  parietal,  between  which  and  the  interparietal  is  a  broad  mem- 
branous area. 

Lateral  to  the  exoccipital,  between  it  and  the  parietal  and  squamosal,  is  a  deep  depression, 
filled  in  the  natural  condition  of  the  parts  with  dense  connective  tissue.  On  the  removal  of  this, 
the  otic  capsule  is  exposed  presenting  a  surface  concavo-convex  dorsoventrad  and  rising  almost  to 
the  level  of  adjacent  bones  as  it  approaches  the  base  of  the  skull,  where  it  is  joined  by  the  hyoid 
bar.  Here  the  facial  nerve  emerges  on  the  caudal  aspect  of  the  stylo-hyal. 

Ventral  to  the  exoccipitals  appears  the  auditory  bulla,  and  in  the  angle  between  it  and  the 
ex-  and  basi-occipital  is  the  jugular  foramen,  which  affords  passage  to  the  hypoglossal  nerve  in 
addition  to  the  ninth,  tenth  and  eleventh,  there  being  no  condyloid  foramen.  The  jugular 


SCHULTE,  SEI  WHALE.  475 

foramen  is  divided  by  membrane  into  a  mesal  compartment  for  the  nerves  mentioned  above 
and  a  lateral  one  for  the  jugular  vein. 

Norma  verticalis. —  The  norma  verticalis  differs  from  that  of  the  adult  not  only  in  the  short 
and  broad  rostrum,  but  even  more  conspicuously  in  the  broad  and  rounded  form  of  the  brain- 
case  and  its  great  size  as  compared  with  the  laterally  projecting  portions  of  the  squamosal  and 
frontal.  The  interparietal  is  single,  free,  and  of  a  pentagonal  shape.  The  supra-occipital  is  in 
contact  with  it  caudad  and  is  beginning  to  override  its  caudal  margin,  but  only  to  a  very  slight 
degree.  Except  at  this  border  it  is  surrounded  by  a  wide  fontanelle  of  complicated  outline, 
which  at  the  sides  extends  to  the  parietals  and  frontals,  rostrad  to  the  frontals  which  are  in 
sutural  contact  in  the  median  line.  The  orifice  of  the  nasal  fossa  is  bounded  as  in  the  adult, 
the  nasal  bones  being  short  in  proportion  to  their  breadth;  they  are  slightly  expanded  at  their 
free  extremities.  Their  margins  are  sharp  and  slightly  concave.  The  premaxillse,  in  corre- 
spondence to  the  short  rostrum,  are  less  slender  than  in  the  adult,  but  otherwise  are  closely 
similar.  They  are  separated  by  a  strip  of  cartilage,  the  dorsal  margin  of  the  cartilage  of  the 
septum.  The  maxillae  are  more  broadly  triangular  than  those  of  the  adult.  Their  nasal  processes 
ascend  more  vertically,  in  consequence  of  the  greater  convexity  of  the  forehead,  and  their  mesal 
inclination  is  distinctly  less.  They  are  marked  by  a  high  transverse  ridge  near  their  articulation 
with  the  orbital  plate  of  the  frontal,  which  marks  the  limit  caudad  of  the  origin  of  the  deep 
stratum  of  the  transverse  rostral  muscle;  the  groove  caudal  to  it,  in  which  laterally  the  lachrymal 
is  seen,  gives  attachment  to  part  of  the  occipitofrontalis  and  to  the  muscle  arising  from  the 
supra-orbital  margin.  The  orbital  plate  of  the  frontal  has  a  strong  sagittal  arch,  and  broadens 
laterad  to  the  supra-orbital  margin.  The  postorbital  process  is  slender  and  decurved,  it  is  joined 
to  the  zygomatic  process  of  the  squamosal  by  a  quantity  of  fibrous  tissue,  to  which  is  attached 
on  a  more  ventral  plane  the  zygoma.  The  slenderness  of  these  processes  of  the  frontal  and 
squamosal  and  their  small  degree  of  lateral  projection  are  among  the  striking  differences  of  the 
fcetal  from  the  adult  cranium. 

Norma  basalis. —  The  hard  palate  has  nearly  attained  the  adult  conformation  of  its  com- 
ponent parts.  The  vomer  is  more  exposed  rostrad,  where  the  maxillae  abut  upon  it  by  a  rounded 
margin;  in  their  caudal  thirds  they  begin  to  cover  it  with  their  marginal  plates.  The  palate 
bones  overlap  it  to  a  greater  degree  and  eventually  meet  in  the  midline,  leaving  a  small  knob 
of  the  ventral  border  exposed  caudal  to  them.  The  maxilla  has  a  wide  alveolar  sulcus  in  its 
caudal  half,  which  opens  into  a  large  cavity,  in  which  are  contained  the  dental  anlages  and  which 
the  maxillary  division  of  the  quintal  nerve  enters  from  behind  after  passing  ventral  to  the  orbit. 
Mesal  to  the  alveolar  region  there  is  a  sagittal  concavity  which  becomes  deepest  in  the  region 
where  the  horizontal  plate  of  the  palate  is  received  between  the  mesal  and  lateral  processes  of 
the  maxilla.  The  lateral  border  of  the  maxilla  is  thick  and  convex,  differing  here  in  contour 
as  well  as  in  proportions  markedly  from  the  adult.  The  caudal  extremity  of  the  maxilla  was 
very  imperfectly  ossified  and  covered  by  thick  and  strong  periosteum,  in  the  removal  of  which 
the  delicate  caudal  border  was  damaged.  So  far  as  could  be  ascertained  this  portion  of  the 
£>one  was  blunt  and  rounded  and  did  not  end  in  a  thin  sharp-edged  plate,  as  in  the  adult,  resem- 
bling in  this  respect  less  modified  types  of  maxillae.  The  orbital  process  is  deeply  grooved 
between  the  alveolus  and  the  orbital  margin  for  the  passage  of  branches  of  the  facial  nerve  and 
vessels  to  the  dorsum  of  the  rostrum. 

The  horizontal  plate  of  the  palate  requires  no  special  comment;   the  vertical  plate  is  short 


476  SCHULTE,  SEI  WHALE. 

and  narrow.     It  is  inserted  between  the  tuberosity  of  the  maxilla  and  the  internal  pterygoid. 
Between  its  summit  and  the  presphenoid  is  a  moderate  sphenopalatine  foramen. 

The  internal  pterygoid  appears  on  the  base  between  the  palate  and  the  external  pterygoid, 
sending  a  narrow  process  dorsad  which  joins  and  underlies  a  descending  process  of  the  frontal. 
The  hamular  processes  are  very  large,  curving  ventrad  and  mesad  and  overhanging  the  audi- 
tory bulla.  The  exposed  surface  of  the  external  pterygoid  is  interposed  between  the  squamosal 
and  internal  pterygoid,  and  lies  in  the  same  plane  as  these  bones,  with  which  it  is  suturally 
united.  From  its  junction  with  the  latter  arises  the  m.  pterygoideus  externus,  the  internus 
taking  origin  from  the  internal  pterygoid  and  that  margin  of  the  palate  bone  which  articulates 
with  it.  There  is  thus  no  pterygoid  fossa. 

From  the  basisphenoid  the  small  triangular  processus  alaris  projects  laterad  nearly  at  the 
level  of  the  dorsal  surface  of  the  sella  turcica.  This  is  still  wholly  cartilaginous.  It  is  continued 
laterad  by  the  processus  ascendens  alae  temporalis,  in  which  ossification  has  begun.  The  latter 
process  is  cylindrical,  slightly  expanded  at  its  extremity,  which  ascends  and  conies  to  the  surface 
in  the  temporal  fossa  in  the  interval  between  the  parietal,  squamosal  and  external  pterygoid. 
In  the  adult  Balcenoptera  a  bone  presenting  in  this  position  has  been  taken  by  Carte  and  Mac- 
Alister  1  for  basisphenoid,  and  Dwight 2  concurs  in  this  usage,  remarking  that  he  does  so  "from 
information  derived  from  the  works  of  other  observers,  for  it  would  be  impossible  to  name  it 
from  the  little  that  is  seen  on  the  unopened  skull."  He  states  that  in  B.  musculus  it  lies  between 
the  parietal  and  the  alisphenoid;  in  B.  rostrata  (=  acuto-rostrata) ,  he  quotes  Carte  and  Mac- 
Alister  as  finding  it  in  contact  also  with  the  squamosal.  As  a  matter  of  literal  fact  they  say 
mastoid,  but  as  this  is  inconceivable,  I  prefer  with  Dwight  to  take  their  meaning  to  be  squa- 
mosal. As  this  region  of  the  skull  is  highly  specialized  and  in  the  adult  many  of  the  sutures 
are  obliterated,  it  is  not  surprising  that  attempts  at  its  analysis  on  the  basis  of  adult  material 
alone  should  have  been  largely  erroneous.  The  matter  is  much  simpler  in  the  light  of  deBurlet's 3 
fine  studies  of  the  chondrocranium  in  Cetacea,  which  have  revealed  the  small  size  and  cylindrical 
form  of  the  ala  temporalis.  In  his  reconstruction  of  B.  rostrata  ( =  acuto-rostrata)  this  process, 
which  corresponds  in  shape  and  position  closely  with  that  of  this  foetus,  projects  freely  into  the 
wide  fenestra  sphenoparietalis,  its  extremity  approaching  close  to  the  orbitoparietal  commissure. 
It  is  therefore  evident,  that,  when  the  fenestra  is  closed  by  the  development  of  membrane  bones, 
their  margins  will  come  in  contact  with  the  ala  temporalis,  the  extremity  of  which  will  appear 
in  the  definitive  temporal  fossa  as  is  usual  in  mammals,  the  peculiarity  of  the  Cetacean  skull 
consisting  merely  in  the  small  size  of  the  ala  temporalis  (alisphenoid) . 

If,  then,  the  basisphenoid  of  the  authors  quoted  becomes  ala  temporalis,  a  reinterpretation 
is  necessary  of  the  ventrally  placed  element,  which  they  take  for  alisphenoid.  This  I  have 
already  described  as  external  pterygoid.  Carte  and  MacAlister,  to  be  sure,  term  it  alisphenoid 
or  pterygoid  bone,  but  then  state  that  ventrally  it  divides  into  two  pterygoid  plates,  which 
include  between  them  a  large  ovoid  pterygoid  fossa.  I  have  already  expressed  the  opinion 
that  the  pterygoid  fossa  is  absent  in  this  skull,  from  which  it  follows  that  the  fossa  here  in  ques- 
tion must  receive  another  interpretation.  I  take  it  to  be  the  scaphoid  fossa.  To  substantiate 

1  Carte  and  MacAlister,  op.  cit.,  p.  208. 

2  Dwight,  T.     Description  of  the  whale  (Balaenoptera  musculus  Auct.)  in  the  possession  of  the  Society,  with  remarks  on  the  classi- 
fication of  fin  whales.     Mem.  Boston  Soc.  Nat.  Hist.,  1871,  Vol.  11,  p.  208. 

MeBurlet,  H.  M.  Zur  Entwicklungsgeschichte  des  Walschadels,  III.  Das  Primordialcranium  eines  Embryo  von  Balamoptera 
rostrata  (105  mm.).  Morph.  Jahrb.,  Bd.  49,  1914,  p.  119.  Cf.  also  I.  and  II.,  Morph.  Jahrb.,  Bd.  45  and  Bd.  47,  p.  644.  Phocama 
communis;  and  IV.  Morph.  Jahrb.,  Bd.  49,  p.  393.  Lagenorhynchus  albirostris. 


PLATE  LIV. 


PLATE  LIV. 

Bdcenoptera  borealis. 


Fig.  1.     Skull,  norma  verticalis.     Twice  natural  size. 
Fig.  2.     Skull,  norma  basalis.     Twice  natural  size. 

1 .  Maxilla. 

2.  Premaxilla. 

3.  Nasal. 

4.  Mesethmoid. 

5.  Lachrymal. 

6.  Frontal. 

7.  Anterior  temporal  ridge. 

8.  Postorbital  process. 

9.  Zygoma. 

10.  Alveolar  gutter. 

11.  Zygomatic  process  of  temporal. 

12.  Squamosal. 

13.  Parietal. 

14.  Exoccipital. 

15.  Supraoccipital. 

16.  Interparietal. 

17.  Vomer. 

18.  Palate. 

19.  Orbital  plate  of  frontal. 

20.  Ala  orbitalis. 

21.  Sphenoidal  fissure  confluent  with  optic  foramen. 

22.  Ala  temporalis. 

23.  Internal  pterygoid  plate. 

24.  Hamular  process. 

25.  External  pterygoid  plate. 

26.  Processus  falciformis  of  squamosal. 

27.  Foramen  ovale. 

28.  Meckel's  cartilage. 

29.  Postglenoid  proceas  of  squamosal. 


30.  External  auditory  meatus. 

31.  Os  tympanicum. 

32.  Stylohyal. 

33.  Stylomastoid  foramen. 

34.  Jugular  foramen. 

35.  Exoccipital  ossification  centre. 

36.  Basioccipital  ossification  centre. 

37.  M.  pterygoideus  internus. 

38.  M.  pterygoideus  externus. 

39.  M.  masseter. 

40.  M.  depressor  mandibulse. 

41.  Mm.  scalenus  et  recti  capitis  antici. 

42.  M.  rectus  capitis  lateralis. 

43.  Mm.  recti  capitis  postici. 

44.  M.  trachelo-occipitalis. 

45.  M.  longissimus. 

46.  M.  obliquus  superior. 

47.  M.  sternomastoideus. 

48.  M.  mastohumeralis. 

49.  M.  trachelomastoideus. 

50.  M.  semispinalis  capitis. 

51.  M.  occipitalis. 

52.  M.  frontalis. 

53.  M.  temporalis. 

54.  M.  transversus  rostralis,  deep  portion. 

55.  The  same,  superficial  portion. 

56.  Oblique  nerial  muscle. 

57.  M.  retractor  naris. 

58.  Fontanelle. 


loirs  Am.  Mus.  Xat.  Hist. 


N.  S,  Vol.  I,  Plato  LIV 


O 

w 


SCHl'LTK,  SKI  \VHALE.  477 

this  view  it  is  necessary  to  enter  into  details.  The  external  pterygoid,  the  ectal  surface  of 
which  has  been  described,  is  not  a  thin  plate  but  a  massive  bone  of  irregular  pyramidal  shape. 
By  its  summit  entally  it  joins  the  as  yet  cartilaginous  processus  alaris,  beyond  which  it  is  con- 
tinuous with  the  base  of  the  processus  ascendens.  It  thus  conforms  literally  to  the  definition 
of  the  external  pterygoid,  being  a  descending  process  of  the  alisphenoid  and  ossifying  from  a 
centre  common  to  it  and  the  processus  ascendens.  Notwithstanding  this  typical  conformation 
in  the  basal  region,  we  are  confronted  ectally  in  the  temporal  fossa  with  a  suture  between  the 
ala  temporalis  and  the  external  pterygoid,  and  it  is  this  highly  aberrant  and  peculiar  character 
which  requires  explanation.  In  less  modified  skulls  these  elements  ectally  are  widely  separated, 
a  portion  of  the  zygomatic  fossa  intervening  between  them.  Here  it  appears  that  incident  to 
the  expansion  of  the  external  pterygoid  to  a  pyramidal  mass,  it  has  come  to  be  secondarily 
appressed  to  the  ala  temporalis  (alisphenoid)  with  concomitant  reduction  of  the  zygomatic 
fossa,  the  highly  significant  remnant  of  which,  and  index  of  the  whole  process,  persists  as  the 
suture  between  the  external  pterygoid  and  alisphenoid. 

The  caudal  surface  of  the  external  pterygoid  is  exposed  on  removal  of  the  otic  capsule.  Dor- 
sad it  extends  to  the  processus  alaris,  ventrad  to  the  base  of  the  hamular  process,  from  which  it 
is  separated  by  a  suture.  Laterad  the  bone  is  drawn  out  into  a  stout  process,  which  lying  mesal 
to  the  foramen  ovale,  is  superficially  overlain  by  the  squamosal,  so  that  the  ectal  orifice  of  the 
foramen  lies  in  the  suture  between  that  bone  and  the  external  pterygoid.  The  apex  of  this  pro- 
cess touches  and  is  very  firmly  united  by  fibrous  tissue  to  the  tegmen  tympani.  Mesad  the 
external  pterygoid  extends  to  the  nasal  fossa  and  here  intervenes  between  the  hamular  and  vagi- 
nal processes.  These  are  both  of  large  size,  and  immediately  rostral  to  them  the  external  ptery- 
goid comes  into  the  lateral  wall  of  the  nasal  fossa,  to  a  degree  usurping  the  place  of  the  internal 
pterygoid  plate  and  taking  part  in  the  formation  of  the  choanse.  The  caudal  surface  of  the 
external  pterygoid  is  crossed  by  a  transverse  ridge  extending  from  the  lateral  process  to  its 
mesal  margin  opposite  the  vaginal  process.1  Dorsal  to  this  ridge  the  surface  is  concave  and  in 
apposition  with  the  first  turn  of  the  cochlea.  Ventrally  the  surface  is  also  concave  and  lodges 
the  Eustachian  tube,  giving  origin  also  to  the  tensor  tympani.  For  this  reason  it  seems  that 
the  concavity  bounded  by  this  surface  laterad  and  rostrad,  and  mesally  by  the  vaginal  process, 
should  be  considered  scaphoid  and  not  pterygoid  fossa. 

Beauregarde,  in  his  description  of  this  region  in  a  young  specimen  of  B.  rostrata  ( =  acuto- 
rostrata),  records  essentially  similar  conditions.  The  fossa  in  the  pterygoid  is  ovoid,  it  is  limited 
"en  dedans  par  un  crete  eleV6e  fournie  par  le  pterygo'ide,  en  avant  par  une  apophyse  digitiforme 
de  pterygo'ide  que  fait  saillie  en  dedans,  au  dessous  de  la  crete  susdite  et  qui  limite  entre  elle  et 
cette  crete  un  espace  dans  lequel  passe  la  trompe  d'Eustache."  The  last  fact  and  his  excellent 
illustration  makes  it  clear  that  the  structures  in  question  are  the  vaginal  and  hamular  processes 
of  the  internal  pterygoid  plate. 

The  internal  pterygoid  lies  in  general  rostrad  of  the  external,  in  which  relative  position  it 
appears  both  on  the  ectal  surface  of  the  skull  and  in  the  nasal  fossa.  Ectally  it  overrides  the 
external  pterygoid  by  its  caudal  margin,  while  its  vaginal  process  is  prolonged  on  the  mesal, 
its  hamular  process  on  the  ventral  aspect  of  the  latter  bone.  Thus  the  external  pterygoid  is 
mortised  into  the  internal  from  behind. 

The  squamosal  in  ventral  view  has  a  triradiate  form;  the  stout  zygomatic  process  projects 

1  Cf .  Beauregarde,  H.     Recherches  sur  1'appareil  auditif  chez  les  mammif6res.     Jour,  de  1'Anat.  et  de  la  Phys.,  An.  XXIX. 


478  SCHULTE,  SEI  WHALE. 

laterad  and  rostrad  to  articulate  with  the  zygoma  and  postorbital  process  of  the  frontal;  the 
more  slender  postglenoid  process  is  directed  ventrad  and  caudad  and  gives  attachment  to  the 
dense  fibrous  envelope  of  the  auditory  meatus  as  well  as  to  the  capsule  and  fibro-cartilage  of 
the  temporo-maxillary  joint;  mesad  and  rostrad  a  narrow  plate,  the  ventral  surface  of  the 
squama,  extends  to  the  external  pterygoid  and  represents  the  glenoid  region.  In  the  line  of 
union  is  situated  the  foramen  ovale.  This  is  bounded  mesad  by  a  process  of  the  squamosal, 
which  overlies  the  pointed  caudal  extremity  of  the  external  pterygoid.  It  is  the  processus 
falciformis  of  Beauregard,  and  in  this  foetus  is  broad  and  very  short  in  comparison  to  its  pro- 
portions in  his  adult  of  B.  musculus  (  =  physalus).  The  angle  between  this  process  and  the  post- 
glenoid is  filled  with  dense  fibrous  tissue  through  which  Meckel's  cartilage  makes  its  way  to  the 
tympanum.  Rostrad  the  glenoid  region  is  separated  from  the  squama  by  a  ridge,  which  sweeps 
laterad  to  the  ental  surface  of  the  zygomatic  process,  and  here  becoming  more  prominent  affords 
a  very  definite  boundary  between  the  temporal  and  zygomatic  fossae;  thus  corresponding  to 
the  anterior  root  of  the  zygoma  and  the  beginning  of  the  infratemporal  crest. 

Of  the  elements  of  the  basicranial  axis  only  the  basi-occipital  is  exposed,  the  basisphenoid 
being  covered  by  the  expanded  alae  of  the  vomer  and  their  articulations  with  the  vaginal  pro- 
cesses. The  basi-occipital  is,  relative  to  that  of  the  adult,  very  long.  It  lies  in  a  deep  depression 
between  the  auditory  bullae,  and  on  each  side  sends  ventrad,  a  low  falcate  process  to  which  the 
fibrous  wall  of  the  bullae  is  attached.  These  ridges  serve  also  for  the  insertion  of  the  rectus- 
scalene  tendon.  Rostrad  they  become  lower  but  can  be  followed  to  the  vaginal  processes.  Here 
laterally  placed  and  partially  overlapped  by  the  vaginal  process  is  the  ectal  orifice  of  the  canal 
in  the  basisphenoid  for  the  internal  carotid  artery.  The  exoccipitals  extend  caudad  of  the  bullae 
to  the  exposed  bases  of  the  otic  capsules,  which  appear  between  them  and  the  squamosals,  here 
articulating  with  the  hyoid  bars,  and  on  their  caudomesal  aspects  giving  passage  to  the  facial 
nerves.  Between  the  exoccipital  and  the  bulla,  is  the  large  posterior  lacerated  foramen  which 
is  divided  by  membrane  into  two  compartments,  a  mesal  one  for  the  IX-XII  nerves,  and  a  lateral 
one  for  the  jugular  vein. 

The  enormous  auditory  bulla  occupies  the  region  between  the  external  pterygoid,  the  squa- 
mosal, the  basi-  and  ex-occipital.  Laterad  it  is  prolonged  into  the  external  auditory  meatus 
which  is  directed  to  the  notch  in  the  squamosal  dorsal  to  its  postglenoid  process.  Its  wall  is 
composed  of  extremely  thick  lamellated  connective  tissue,  which  is  attached  mesad  and  caudad 
to  the  vaginal  process  and  occipital,  rostrad  and  laterad  to  the  external  pterygoid,  squamosal, 
and  otic  capsule,  and  is  prolonged  upon  the  floor  of  the  auditory  meatus.  In  this  fibrous  capsule 
is  embedded  the  tympanic,  which  is  relatively  of  small  size  and  irregularly  crescentic  in  form. 
It  sends  two  cornua  laterad.  Of  these  the  caudal  is  far  the  longer  and  extends  to  the  base  of 
the  otic  capsule,  to  which  it  is  loosely  attached  by  connective  tissue.  The  rostral  cornu  is  situated 
caudal  to  Meckel's  cartilage,  where  it  ends  without  other  than  membranous  attachment  to 
adjacent  structures.  Save  at  one  point  the  tympanic  is  then  isolated  from  other  bones,  and 
constitutes  at  this  time  a  small  plate  in  the  extensive  fibrous  wall  of  the  bulla.  The  size  of 
the  auditory  bulla  makes  it  the  dominant  feature  of  this  region  of  the  skull,  and  joined  to  the 
small  development  of  the  squamosal,  and  the  relatively  long  basi-occipital,  renders  the  basis 
cranii  at  this  stage  of  development  exceedingly  dissimilar  from  that  of  the  adult. 

Norma  lateralis.  The  high  convexity  of  the  cranium,  the  concavity  at  its  junction  with 
the  rostrum,  the  horizontal  base-line,  together  with  the  less  prominent  orbital  margin  and  zygo- 


SCHULTE,  SEI  WHALE.  47!) 

matic  process  of  the  squamosal,  and  the  much  less  projection  caudad  of  the  postglenoid  process, 
combine  to  lend  this  aspect  of  the  skull  also  an  appearance  very  different  from  that  of  the  adult. 
In  particular  the  undeveloped  processes  and  rostrum  render  the  brain  case  more  prominent, 
which  to  be  sure  is  usual  in  fcetal  skulls,  but  is  more  than  ordinarily  striking  in  this  instance  on 
account  of  the  enormous  size  ultimately  attained  by  these  projections.  The  temporal  ridge 
is  present  only  rostrad  and  here  ascends  from  the  orbital  margin  with  a  caudal  curvature  a  short 
distance  upon  the  frontal,  marking  the  limit  of  the  origin  of  the  temporal  muscle  in  this  direc- 
tion. Elsewhere  on  the  cranial  wall  the  fossa  is  without  definite  limits.  The  ridge  before 
mentioned  upon  the  maxillary  is  clearly  outside  the  confines  of  the  fossa.1  In  the  adult 2  the 
configuration  of  this  region  changes  markedly  and  the  maxillary  ridge  is  continuous  with  the  crest 
that  bounds  the  temporal  fossa,  the  fcetal  ridge  above  the  supraorbital  margin  being  no  longer 
recognizable.  The  dorsal  surface  of  the  orbital  process  of  the  maxillary  and  the  whole  of  the 
orbital  plate  of  the  frontal  are  thus  within  the  arch  of  the  united  ridges.  The  temporal  muscle 
cannot  occupy  the  whole  of  this  extensive  surface.  Carte  and  MacAlister  expressly  state  that 
in  R.  rostrata  (=  acuto-rostrata)  it  does  not  extend  forward  beyond  the  posterior  angle  of  the 
orbit  and  the  maxillary  surface  is  already  preempted  by  the  frontalis  muscle. 

The  zygomatic  process  of  the  squamosal  projects  strongly,  but  is  more  slender  than  in  the 
adult.  From  its  junction  with  the  zygoma  and  the  postorbital  process  of  the  frontal  a  strong 
tendinous  reinforcement  of  its  periosteum  extends  to  the  caudal  margin  of  the  bone,  where  it 
overlies  the  otic  capsule.  The  insertions  of  the  sterno-mastoid,  masto-humeral,  trachelo-mastoid 
and  splenius  are  prolonged  upon  the  tendon  and  the  fibrous  tissue  covering  the  otic  capsule, 
but  can  hardly  at  this  period  of  development  be  said  to  insert  upon  the  mastoid  itself,  for  this 
process  is  still  in  a  most  rudimentary  condition.  The  postglenoid  process  is  directed  caudad 
and  ventrad  in  front  of  the  external  auditory  meatus  which  is  lodged  in.  a  notch  between  this 
process  and  the  caudal  part  of  the  squama.  It  is  separated  dorsad  from  the  superior  root  of  the 
zygomatic  process  by  a  shallow  groove.  Its  surface  especially  rostrad  is  covered  by  a  very  thick 
periosteum.  Caudal  to  the  squama  an  oval  surface  of  the  otic  capsule  is  exposed.  Caudal 
again  is  the  extremity  of  the  exoccipital,  mesad  of  which  the  convexity  of  the  occipital  condyle 
is  just  visible,  in  profile  forming  the  most  caudal  point  of  the  skull.  Important  changes  in  pro- 
portion occur  in  this  region  subsequently  and  depend  in  the  main  upon  the  enormous  enlarge- 
ment of  the  postglenoid  process  which  eventually  projects  beyond  and  conceals  the  condyle 
in  profile  view. 

Orbit. —  A  complete  osseous  roof  is  afforded  by  the  orbital  process  of  the  frontal;  this  broadens 
laterad  to  its  pre-  and  post-orbital  processes,  the  latter  of  which  is  prolonged  into  a  strong  pro- 
cess far  less  massive  than  in  the  adult,  which  joins  the  zygomatic  process  of  the  squamosal  by 
means  of  a  mass  of  fibrous  tissue  interposed  between  their  extremities.  Ventrad  this  bar  is 
produced  into  a  plate,  which  affords  a  partial  caudal  wall  to  the  orbit.  The  preorbital  margin 
of  the  frontal  is  prolonged  into  a  similar  ventrally  directed  plate,  the  mesal  extremity  of  which 
descends  in  a  stout  process  which  overlies  the  ascending  process  of  the  internal  pterygoid  and 
abuts  caudad  upon  a  similar  process  of  the  external  plate.  Mesad  the  orbital  surface  of  the 
frontal  terminates  in  an  arched  margin  of  dorsal  convexity  which  connects  the  mesal  end  of  the 

1  A  similar  configuration  of  this  region  is  shown  in  the  skull  of  Cetotherium.      Cf.  Abel,  O.     Die  vorzeitlichen  Saugetiere.     1914. 
Fig.  53.     Also  in  Rhachianectes.     Cf.  Andrews,  R.  C.     The  Calfornia  Gray  Whale.     Mem.  Am.  Mus.  Nat.  Hist.,  N.  S.,  Vol.  1,  Pt.  V., 
pi.  xxvii. 

2  Cf.  Andrews,  R.  C.     This  memoir  pi.  XLII. 


480  SCHULTE,  SKI  WHALE. 

postorbital  plate  with  the  descending  process  of  the  preorbital.  This  arch  abuts  against  the 
flat  cartilaginous  orbito-sphenoid,  which  overlaps  the  frontal  on  its  cranial  surface,  and  mesally 
completes  the  roof  of  the  orbit.  The  distance  between  the  ends  of  the  frontal  arch  just  described 
is  10  mm.,  that  between  the  lateral  extremities  of  its  pre-  and  postorbital  processes  is  21  mm. 
The  depth  of  the  orbital  plate  is  11  mm.  It  is  thus  evident  that  the  orbital  plate  of  the  frontal 
has  a  more  flaring  form,  and  in  particular  is  transversely  far  shorter  than  in  the  adult.  A 
further  difference  lies  in  the  complete  exposure  of  its  orbital  surface  in  its  whole  extent,  and  the 
absence  of  any  overrolling  on  the  part  of  the  preorbital  plate  or  of  the  postorbital,  such  as  occurs 
in  the  subsequent  transverse  lengthening  of  the  orbital  process,  with  the  result  of  reducing  the 
orbital  roof  to  a  small  triangle  at  its  lateral  end,  and  the  concealment  and  exclusion  of  the  orbito- 
sphenoid  from  this  secondary  orbital  cavity. 

The  floor  of  the  orbit  is  almost  wholly  membranous.  Ventral  to  the  preorbital  plate  of  the 
frontal  a  triangular  surface  of  maxilla  presents  in  the  floor  and  articulates  with  the  zygoma. 
The  latter  is  very  slender,  ventrally  convex,  slightly  expanded  at  its  ends,  having  mesal  and 
lateral  margins  and  dorsal  and  ventral  surfaces.  To  its  mesal  margin  the  suborbital  aponeurosis 
is  attached.  At  the  mesal  extremity  of  the  orbit,  the  external  pterygoid  plate  forms  a  ledge 
•  ventrally  comparable  to  the  frontal  arch  dorsally,  but  less  regular  and  lying  in  a  more  lateral 
position  relative  to  the  ala  orbitalis  and  the  body  of  the  sphenoid,  to  which  latter  it  is  here  joined 
by  a  considerable  mass  of  connective  tissue.  Caudad  the  margin  is  completed  by  the  ala  tem- 
poralis  and  by  the  ventral  angle  of  the  parietal,  the  margin  of  which  participates  in  the  ledge  and 
continues  it  to  the  mesal  extremity  of  the  postorbital  plate  of  the  frontal.  The  ledge  thus  con- 
stituted serves  for  the  mesal  attachment  of  the  suborbital  aponeurosis,  which  caudally  joins 
the  edge  of  the  postorbital  plate  and  rostrad  is  connected  to  the  orbital  process  of  the  maxillary, 
the  preorbital  plate  of  the  frontal,  and  its  descending  process.  As  a  whole  the  floor  of  the 
orbit  is  less  convex  than  the  roof,  it  is  however  longer  transversely,  for  the  zygoma  is  more 
laterally  placed  than  the  receding  supra-orbital  margin.  The  intimate  relation  of  the  floor  of 
the  orbit  ventrad  with  the  vestibulum  oris  has  already  been  mentioned,  as  has  also  the  insertion 
of  the  superficial  division  of  the  masseter  into  its  aponeurosis. 

The  apical  region  of  the  orbit  between  the  frontal  arch  and  the  infraorbital  ledge  is  closed 
by  the  orbito-sphenoid  and  a  portion  of  the  presphenoid.  These  arches  form  together  an  oval 
with  its  long  axis  obliquely  directed  caudad  and  ventrad.  In  this  aperture  appears  above  a 
broad  flat  surface  of  orbito-sphenoid.  Caudo-ventrad  to  this  is  the  large  sphenoidal  fissure, 
at  the  ventro-rostral  margin  of  which  appears  a  portion  of  the  presphenoid.  This  is  separated 
by  a  fibrous  interval  from  the  external  pterygoid.  The  optic  foramen  pierces  the  orbito-sphenoid 
below  its  middle,  and  is  connected  by  a  narrow  cleft  in  the  cartilage  with  the  sphenoidal  fissure, 
from  the  contents  of  which  the  optic  nerve  is  separated  by  a  broad  partition  of  connective  tissue. 
The  sphenoidal  fissure  in  addition  to  its  usual  contents,  transmits  the  maxillary  division  of  the 
fifth  nerve. 

Cranial  cavity. —  The  long  axis,  extending  from  the  foramen  magnum  to  the  dorsal  margin 
of  the  frontal  ossification  centre,  is  approximately  parallel  to  the  basis  cranii  and  has  a  length 
of  49  mm.  The  greatest  dorso-ventral  diameter,  between  the  rostral  margin  of  the  supra- 
occipital  and  the  sella  turcica  is  29  mm.,  and  the  greatest  transverse,  which  falls  in  the  same 
plane,  is  40  mm.  Caudad  of  this  transverse  plane  the  cavity  narrows  like  a  funnel  to  the  foramen 
magnum,  while  rostrad  it  is  rounded  and  broadly  concave  in  the  frontal  region.  The  floor  is 


PLATE  LV. 


PLATE  LV. 


Bakenoptera  borealis. 


Fig.  1.     Skull,  norma  occipitalis.     Twice  natural  size. 
Fig.  2.     Skull,  norma  lateralis.     Twice  natural  size. 

1.  Interparietal. 

2.  Superior  fontanelle. 

3.  Parietal. 

4.  Squamosal. 

5.  Zygomatic  process. 

6.  Postorbital  process  of  frontal. 

7.  Optic  foramen. 

8.  Exoccipital.  37. 

9.  Supraoccipital. 

10.  Occipital  condyle. 

11.  Lateral  fontanelle.  40. 

12.  Otic  capsule.  41. 

13.  Stylohyal.  42. 

14.  Postglenoid  process  of  squamosal. 

15.  Hamular  process. 

16.  Jugular  foramen,  compartment  for  vein.  45. 

17.  Jugular  foramen,  compartment  for  nerves. 

18.  Auditory  bulla.  47. 

19.  External  auditory  meatus.  48. 

20.  Paroccipital  process.  49. 

21.  Exoccipital  ossification  centre.  50. 

22.  M.  semispinalis.  51. 

23.  Mm.  recti  postici. 

24.  Mm.  recti  antici  et  scalenus.  52. 

25.  M.  rectus  lateralis.  53. 

26.  M.  obliquus  superior.  54. 

27.  M.  longissimus  dorsi.  55. 

28.  M.  trachelo-occipitalis.  56. 

29.  M.  depressor  mandibulae.  57. 


M.  splenius. 

M.  trachelo  mastoideus. 

M.  sternomastoideus. 

M.  mastohumeralis. 

Frontal. 

Lachrymal. 

Orbital  process  of  maxilla. 

Descending  process  of  frontal. 

Ala  orbitalis. 

•Palate. 

Internal  pterygoid. 

External  pterygoid. 

Ala  temporalis. 

Sphenoidal  fissure. 

Maxilla. 

Transverse  rostral  muscle,  superficial  layer. 

Transverse  rostral  muscle,  deep  layer. 

Retractor  naris. 

Oblique  narial  muscle. 

Nasal  bone. 

Premaxilla. 

Insertion    of   deep   stratum    of   occipito-frontalis    and    of 

supra-orbital  muscle. 

Attachment  of  ligamentum  apicis  dentis. 

Origin  of  supraorbital  muscle. 

M.  masseter. 

M.  sternomandibularis. 

Septal  cartilage. 

M.  temporalis. 


Memoirs  Am.  Mus.  Nat.  Hist. 


X.  S.,  Vol.  I,  Plate  LV. 


g-  1. 


1  2 


,22 


53 


Fig.  2. 
BALuENOPTERA   BOREALIS. 


SCHULTE,  SEI  WHALE.  481 

obliquely  directed,  rising  rostrad  and  making  an  angle  of  about  30°  with  the  long  axis  of  the 
head.  With  the  dura  in  place  the  cavity  is  smooth  walled,  the  irregularities  between  the  bones 
being  filled  with  dense  connective  tissue;  especially  is  this  the  case  around  the  otic  capsule.  The 
falx  cerebri  is  narrow,  beginning  upon  the  mesethmoid  which  has  a  low  median  ridge  for  its 
attachment,  and  extending  to  the  supra-occipital  where  it  meets  the  tentorium.  Beyond  this 
the  falx  cerebelli  is  represented  by  a  minimal  median  fold.  The  tentorium  is  broader  than  the 
falx;  it  rises  steeply,  its  plane  making  an  angle  of  about  70°  with  the  basis  cranii.  Its  aperture 
is  elongated  dorso-ventrally,  contracted  from  side  to  side.  Ventrad  its  margin  broadens  to  its 
attachment  to  the  rudimentary  dorsum  sellse  and  the  side  of  the  shallow  sella  turcica.  A  second 
low  fold  of  dura  extends  from  the  dorsal  margin  of  the  foramen  magnum  obliquely  ventrad  and 
rostrad,  terminating  in  an  arch  which  surrounds  the  porus  acousticus  internus  on  its  dorsal  and 
rostral  contours.  Beneath  the  middle  third  of  this  fold  is  the  jugular  foramen,  divided  by  dura 
into  a  rostral  compartment  for  the  hypoglossal,  this  subdivided  into  two  parts,  for  the  nerve 
pierces  the  dura  in  two  divisions,  and  a  caudal  one  for  the  glossopharyngeal  and  vago-accessorius. 
The  facial  and  acoustic  nerves  as  noted  above  pass  out  beneath  its  extremity,  while  the  fifth 
has  a  large  dural  foramen  midway  between  this  fold  and  the  tentorium.  For  the  rest,  the 
posterior  fossa  offers  little  to  comment  upon;  its  floor  is  concave  and  rises  caudad  to  the  fora- 
men magnum,  so  that  the  region  of  the  clivus  does  not  form  a  continuous  ascent. 

The  middle  and  anterior  cerebral  fossae  are  but  very  imperfectly  demarcated  on  the  floor, 
owing  to  the  lack  of  prominence  of  the  ala  orbitalis.  This  however  is  recognizable  and  the 
distance  from  its  caudad  margin  to  the  rostral  pole  of  the  cavity  exceeds  that  from  the  same  point 
to  the  tentorium.  The  anterior  fossa  appears  therefore  enlarged  at  the  expense  of  the  middle. 
The  sella  turcica  is  shallow  but  broad,  and  the  cavity  in  the  dura  which  lodges  the  hypophysis 
has  corresponding  proportions.  The  diaphragma  sellse  is  narrow  and  zonular  with  a  large  fora- 
men. The  optic  nerve  enters  the  dura  at  the  side  of  the  olivary  eminence  and  has  a  long  sub- 
dural  course  before  reaching  the  optic  foramen.  The  cribriform  area  is  depressed  and  a  sharp 
lateral  and  rostral  margin  defines  it  from  the  frontal  and  from  the  lateral  ethmoid.  In  it  are 
three  small  foramina  for  olfactory  nerves. 

After  the  removal  of  the  dura  the  conditions  of  the  cranial  elements,  apart  from  the  appear- 
ance of  ossification  centres  and  of  membrane  bones,  was  found  to  correspond  very  closely  to 
the  pattern  of  the  chondrocranium  of  B.  acuto-rostrata  of  105  mm.,  modelled  and  described  by 
deBurlet.  There  are  a  few  changes  however,  the  taenia  metoptica  has  been  partially  absorbed 
so  that  the  optic  foramen  is  now  confluent  with  the  sphenoidal  fissure,  but  otherwise  the  fenes- 
tra  spheno-parietalis  has  much  the  same  shape  and  relative  size  as  in  deBurlet's  model.  The 
commissura  orbito-parietalis  persists  as  a  narrow  and  thin  bar  of  cartilage  at  its  dorso-lateral 
margin,  now  overlain  ectally  by  the  parietal  bone.  Caudally  the  commissura  expands  moder- 
ately and  joins  the  otic  capsule  at  the  origin  of  the  commissura  prsefacialis,  but  here  stops  with- 
out reaching  the  occipital,  so  that  the  lamina  parietalis  seems  largely  to  have  been  absorbed. 
In  consequence  there  is  in  this  region  a  small  lateral  fontanelle  between  exoccipital,  parietal 
and  otic  capsule;  in  the  angle  between  the  two  latter  a  small  triangle  of  squamosal  appears, 
which  in  the  natural  condition  is  covered  by  fibrous  tissue  excluding  it  from  the  cranial  cavity. 

The  fenestra  spheno-parietalis  is  partially  subdivided  by  the  rod-shaped  ala  temporalis. 
This  as  in  deBurlet's  model  falls  short  of  reaching  the  commissura  orbito-parietalis  by  a  narrow 
interval.  The  extremity  of  the  ala  temporalis  appears  in  the  temporal  fossa,  as  has  been  noted 


482  SCHULTE,  SEI  WHALE. 

in  the  account  of  the  exterior  of  the  skull,  between  the  external  pterygoid  and  the  parietal. 
Mesad  it  is  suturally  attached  to  a  process  of  the  basisphenoid  (processus  alaris)  which  completes 
the  boundary  of  the  sphenoidal  fissure  caudad.  Owing  to  the  interval  which  exists  between  the 
lateral  extremities  of  the  ala  temporalis  and  ala  orbitalis  a  small  segment  of  parietal  closes  the 
fissure  at  this  point.  The  sphenoidal  fissure  is  confluent  with  the  optic  foramen,  but  not  broadly 
for  a  remnant  of  the  ta3nis  metoptica  persists  as  a  process  of  the  ala  orbitalis.  In  addition  to 
its  usual  contents  it  transmits  the  maxillary  division  of  the  quintus,  there  being  no  foramen 
rotundum.  Caudal  to  it  is  the  foramen  ovale  at  the  bottom  of  the  triangular  interval  between 
it  and  the  otic  capsule.  This  space  is  largely  filled  with  fibrous  tissue,  upon  the  removal  of 
which  the  ventral  angle  of  the  parietal  and  a  small  area  of  squamosal  are  seen  closing  the  space 
lateral  and  dorsal  to  the  foramen  ovale. 

The  otic  capsule  has  advanced  little  beyond  the  condition  recorded  by  deBurlet.  The  fissura 
basi-capsularis  is  marked  by  a  deep  groove,  in  the  caudal  part  of  which  is  situated  the  jugular 
foramen,  and  more  mesally  but  close  to  it  the  foramen  perilymphaticus  still  confluent  with  the 
fenestra  rotunda.  Rostrad  toward  the  dorsum  sellao  there  is  a  very  broad  basi-cochlear  com- 
missure of  cartilage  and  here  the  surface  of  the  otic  capsule  slopes  into  that  of  the  basisphencid 
without  visible  demarcation.  The  ental  orifice  of  the  carotid  canal  is  situated  as  in  deBurlet's 
model  at  the  caudal  margin  of  the  processus  alaris  with  the  alse-cochlear  commissure  forming 
its  lateral  boundary.  The  canal  begins  ventrad,  at  the  caudal  margin  of  the  internal  pterygoid 
plate  and  is  directed  rostrad,  dorsad  and  laterad  through  the  basisphenoid.  It  is  of  small  di- 
mensions as  the  carotid  artery  is  smaller  than  the  vertebral  in  this  foetus.  The  line  of  attach- 
ment of  the  tentorium  to  the  otic  capsule  is  indicated  by  a  low  ridge  which  terminates  between 
the  foramen  perilymphaticus  and  the  porus  acousticus  internus.  The  latter  is  narrowed  by  a 
zonular  fold  of  dura,  but  in  the  cartilage  gapes  widely  and  is  divided  by  a  ridge  of  cartilage  into 
a  dorsal  and  a  ventral  portion.  The  canalis  facialis  is  hardly  more  roofed  in  than  in  deBurlet's 
foetus  and  the  commissura  prafacialis  is  not  proportionately  increased  in  size.  The  ridge  for 
the  tentorium  becomes  grooved  in  its  dorsal  portion  and  in  this  groove  appears  the  foramen 
endolymphaticus. 

The  ental  surface  of  the  basi-occipital  descends  from  the  foramen  magnum  and  again  rises 
towards  its  junction  with  the  basisphenoid.  Its  ossification  centre,  which  presents  ectally  as  a 
narrow  strip,  expands  towards  the  cerebral  cavity  and  on  its  ental  surface  occupies  the  whole 
breadth  of  the  cartilage.  It  is  separated  from  the  spherical  ossification  centre  of  the  basisphenoid 
by  a  wide  mass  of  cartilage  which  dorsally  projects  as  a  low  ridge  into  the  cranial  cavity.  Ros- 
trad of  this  there  is  a  concavity  which  lodges  the  hypophysis.  The  ridge  must  therefore  be  the 
dorsum  sellse,  the  concavity  the  sella  turcica.  This  in  turn  is  limited  rostrad  by  a  second  low 
transverse  ridge,  the  olivary  eminence,  which  laterally  terminates  in  a  small  conical  projection, 
the  remains  of  the  tsenia  postoptica.  Rostrad  of  this  again  is  a  shallow  concavity,  the  cerebral 
surface  of  the  presphenoid,  in  which  have  appeared  a  pair  of  small  ossification  centres,  which 
have  not  yet  united  in  the  midline.  The  ala  orbitalis  is  very  large  and  terminates  on  the  ental 
surface  of  the  frontal  with  a  concave  margin.  The  tsenia  prooptica  is  broad  and  convex  dorsad 
where  it  forms  the  boundary  of  the  orbito-nasal  foramen  which  gives  passage  to  the  large  nasal 
nerve.  Elsewhere  the  orbito-nasal  fissure  is  reduced  to  linear  dimensions  and  closed  by  mem- 
brane. 

The  large  and  wide  area  between  the  presphenoid  and  the  frontal  is  occupied  by  the  cere- 


PLATE  LVI. 


SCHULTE,  SEI  WHALE.  483 

bral  surface  of  the  nasal  capsule.  The  mesethmoid  in  which  no  centre  of  ossification  has  yet 
appeared,  is  represented  by  a  very  thick  plate  of  cartilage  continuous  caudad  with  the  pre- 
and  basisphenoid  and  extending  the  whole  length  of  the  rostrum  without  as  yet  a  sign  of  division 
into  parts.  To  its  ventral  margin  is  applied  the  broad  trough-like  vomer.  The  cerebral  surface 
of  this  extensive  cartilage  rises  in  the  midline  in  a  low  sagittal  ridge  to  which  is  attached  the  falx 
cerebri.  The  lateral  area  of  the  nasal  capsule  has  ossified  on  its  cerebral  surface,  which  has  a 
quadrangular  outline  and  abuts  by  its  caudal  end  upon  the  orbito-nasal  fissure.  This  lateral 
ethmoid  is  joined  to  the  mesethmoid  by  a  delicate  cribriform  plate,  which  is  slightly  depressed 
and  contains  three  rather  large  foramina.  It  is  still  cartilaginous. 

The  axial  elements  of  the  cranium  are  all  remarkable  for  their  transverse  breadth,  especially 
is  this  true  of  the  sphenoidal  segments,  and  further  for  the  low  relief  of  their  projections,  notably 
the  dorsum  sellse.  There  are  no  clinoid  processes.  As  a  whole  the  brain-case  is  less  elongated 
than  in  deBurlet's  foetus,  but  is  still  far  from  the  shortened  condition  of  the  adult,  from  which 
it  further  differs  in  the  lack  of  any  pronounced  bending  at  its  junction  with  the  rostrum. 

Mandibula. —  The  mandible  is  strongly  arched,  measuring  87  mm.  along  its  convex  ectal 
surface  and  but  75  mm.,  along  the  arc  of  this  curve.  Its  height  at  the  coronoid  process  is 
13.5  mm.,  at  the  condyle  12  mm.  It  differs  from  the  adult  bone  in  the  massive  proportions  of 
its  proximal  portion,  which  far  exceeds  the  body  in  its  vertical  and  transverse  dimensions.  The 
condylar  process  is  better  developed,  and  is  distinctly  produced  craniad,  so  that  the  margin  of 
the  mandibular  notch  ascends  distinctly  towards  the  articular  surface.  The  ventral  margin 
rostrad  of  the  angle  is  slightly  convex  becoming  straight  below  the  coronoid.  In  consequence 
the  whole  post-coronoid  portion  of  the  jaw  has  a  slight  ascent,  the  reverse  of  its  direction  in 
the  adult.  The  articular  surface  is  ovoid,  with  its  major  axis  obliquely  directed  craniad,  mesad 
and  rostrad,  and  in  this  direction  narrowing  to  a  blunt  point.  It  is  covered  by  a  thick  fibrous 
pad  which  joins  it  to  the  glenoid  fossa.  I  could  make  out  no  synovial  cavities,  but  the  tissue 
adjacent  to  the  bones  was  loose  and  easily  stripped  off.  A  firm  capsule  was  attached  at  the 
circumference  of  the  condyle.  An  oblique,  shallow  groove  separates  the  condyle  from  the  re- 
gion of  the  angle,  which  is  elevated  and  massive  giving  attachment  to  the  depressor  mandibulae. 
The  coronoid  process  is  high  and  triangular,  its  caudal  margin  vertical  and  slightly  concave. 
Entally  a  deep  groove  separates  the  condyle  from  the  angular  process  which  is  strongly  marked 
and  massive.  In  the  groove  is  attached  the  internal  pterygoid  muscle.  The  mandibular 
foramen  is  large,  the'  lingula  but  little  developed  and  more  nearly  horizontal  than  in  the  adult. 
Meckel's  cartilage  is  lodged  in  a  groove  near  the  ventral  margin,  and  is  visible  on  the  surface 
from  the  mandibular  foramen  almost  to  the  symphysis  though  much  diminished  in  size  distad. 
From  the  interval  between  the  mandibular  foramen  and  the  insertion  of  the  depressor  craniad 
the  cartilage  is  free,  passing  mesad  of  the  temporo-maxillary  articulation  to  become  continuous 
with  the  malleus.  The  body  of  the  mandible  diminishes  gradually  toward  the  symphysis.  It 
has  the  form  of  a  trough  enclosing  the  large  dental  gutter,  which  begins  immediately  distad  of 
the  coronoid  process. 

Hyoid. —  The  hyoid  is  well  ossified  and  shows  no  sutures  between  its  component  parts. 
The  lesser  cornua  point  directly  rostrad  and  are  separated  by  a  deep  and  narrow  notch.  To  their 
apices  are  attached  the  strong  and  rounded  stylohyoid  ligaments,  which  run  dorsad  to  the 
extremities  of  the  stylohyals.  The  greater  cornua  are  of  large  size,  extending  laterad  and 
slightly  dorsad;  between  their  extremities  the  caudal  border  of  the  bone  is  transverse,  and 


484 


SCHULTE,  SEI  WHALE. 


straight  save  for  two  slight  convexities  near  the  midline  where  the  thyrohyoidei  insert.     The 
greatest  sagittal  extent  is  8  mm.;   the  transverse  distance  between  the  tips  of  the  greater  coruna 

is  29  mm.  The  stylohyals  are  cylindrical  at 
their  attachment  to  the  otic  capsule.  They 
extend  ventrad,  mesad  and  rostrad  to  the 
vicinity  of  the  lesser  coruna  of  the  hyoid. 
Here  their  extremities  are  somewhat  com- 
t  pressed  from  side  to  side.  They  are  carti- 

Fig.  7.     Hyoid.     1,  Stylohyal.     2,  Stylohyal  ligament.     3,  Basio-      laginoUS  in  their  whole  extent, 
keratic  muscle.      4,  Omohyoid.  •  5,  Sternohyoid.      6,  Thyrohyoid. 

7,  Geniogiossus.  Vertebra; : —  In  form  the  vertebrae  corre- 

spond already  quite  closely  to  those  of  the 

adult.     The  tubercles  which  serve  for  muscular  attachment  are  but  feebly  developed  and  the 
surfaces  are  without  muscular  rugosities,  conformably  to  their  cartilaginous  condition,  only  the 
centra  as  yet  being  possessed  of  ossification  centres.     The  vertebral  formula  is  C.  7,  T.  13,  L. 
-C.  35. 

In  view  of  the  differential  growth  of  the  spine,  which  is  an  important  factor  in  determin- 
ing the  form  of  the  thorax  and  abdomen,  a  topic  upon  which  Miiller  has  made  most  interesting 
observations,  the  following  measurements  of  the  length  of  the  bodies  of  the  vertebrae  are  given. 
They  are  taken  from  a  medisection  ©f  the  spine  and  do  not  correspond  exactly  to  the  length  of 
the  ventral  faces  of  the  centra  which  are  somewhat  shorter,  the  vertebrae  of  the  lumbar  and 
caudal  series  being  biconvex,  and  the  disks  biconcave.  In  the  cervical  and  thoracic  regions  the 
centra  are  nearly  flat. 

Measurements  of  the  lengths  of  the  vertebral  centra. 


mm. 

Vertebra 

2  

4. 

« 

3  

2. 

u 

4  

2.1 

tt 

5  

2.4 

ft 

6  

2.5 

a 

7  

2.6 

u 

8  

3. 

it 

9  

3.6 

" 

10  

4. 

tl 

11  

4.2 

tt 

12  

4.4 

tl 

13  

4.5 

It 

14  

5. 

ft 

15  

5. 

tt 

16  

5.2 

tl 

17...  

5.2 

11 

18  

5.5 

tt 

19  

5.8 

It 

20  

6. 

tt 

21  

6. 

tl 

22  

'  6. 

It 

23  

6. 

tl 

24  

6. 

tl 

25  

6. 

<f 

26  

6. 

tl 

27  

6.5 

11 

28  

..6.5 

mm. 

Vertebra  29  

6.5 

30  

(i.7 

31  

7. 

32  

7.1 

33  

7.1 

34  

7.2 

35  

7.3 

36  

7.4 

37  

.*  7.5 

38  

7.5 

39  

7.5 

40  

7.0 

.  "   41  

tt.9 

42  

6.9 

43  

6.6 

44  

6.0 

45  

5.4 

46  

5.0 

"   47  

4.5 

"   48  

4.1 

49  

4.0 

"   50  

3.6 

"   51  

3.0 

"   52  

2.5 

"   53  

2.2 

54  

2.0 

"   55.. 

..1.8 

PLATE  LVII. 


PLATE  LVII . 


Balcenoptera  boratlix. 


Fig.  1. 
Fig.  2. 
Fig.  3. 
Fig.  4. 


Left  mandible,  lateral  view.     Twice  natural  size. 
Left  mandible,  mesal  view.     Twice  natural  size. 
Left  otic  capsule  and  auditory  ossicles,  ventral  view. 
Cervical  vertebra;,  ventral  view.     3  X  natural  size. 


4  X  natural  size. 


1.  M    temporalis. 

2.  M.  masseter,  deep  portion. 

3.  M.  masseter,  superficial  portion. 

4.  M.  depressor  mandibulae  (M.  digastricus,  posterior  belly). 

5.  M.  digastricus,  anterior  belly. 

6.  M.  pterygoideus  interims. 

7.  M.  mylohyoideus. 

8.  Meckel's  cartilage. 

9.  Lingula. 
10.  Malleus. 


11.  Incus. 

12.  Stapes. 

13.  M.  stapedius. 

14.  Canalis  facialis. 

15.  Canalis  semicircularis  externus. 

16.  Tegmen  tympani. 

17.  Cochlea. 

18.  M.  tensor  tympani. 

19.  Foramen,  conducting  vessels  to  the  interior  of  the  cochlea. 


Memoirs  Am.  Mus.  Nat.  Hist. 


N.  S.,  Vol.  I,  Plate  LVII. 


Fig.   1. 


1 


Fig.  4. 


15 


Fig.  3. 
BAL.ENOPTERA  BOREALIS. 


SCHULTE,  SEI  WHALE.  485 

In  all  of  the  bodies  except  the  last  five,  a  center  of  ossification  is  present.  These  in  section 
are  oval  as  far  as  the  midthoracic  region,  beyond  this  circular.  In  the  terminal  vertebrae  the 
cartilage  has  begun  to  calcify  except  in  the  last  two. 

The  spinal  cord  extends  to  the  level  of  the  thirty-second  vertebra,  beyond  which  it  is  con- 
tinued as  the  filum  terminale  surrounded  by  the  nerves  of  the  cauda  equina.  The  neural  arch  is 
lacking  in  the  last  ten  vertebras,  and  in  the  seven  or  eight  vertebrae  rostral  to  these  it  was  of  minute 
dimensions. 

The  intervertebral  disks  are  in  general  biconcave,  expanding  towards  the  periphery  of  the 
centra  and  very  thin  in  the  middle.  The  width  of  the  expanded  circumference  increases  caudad, 
being  greater  opposite  the  larger  chevron  bones.  At  the  end  of  the  series  it  diminishes  rapidly. 
A  few  of  the  disks  of  the  upper  thoracic  region  departed  slightly  from  this  simple  type  showing  a 
small  lenticular  thickening  in  their  centers. 

The  chevron  bones  are  ten,  possibly  eleven  in  number,  the  last  being  so  minute  a  nodule  in 
the  dense  fibrous  tissue  of  the  region  that  I  am  not  sure  it  was  cartilage.  No  joint  was  present 
between  it  and  the  corresponding  intervertebral  disk  as  in  the  case  of  the  other  ten.  The  second 
is  the  longest  of  the  series;  the  last  three  or  four  are  very  small.  The  first  articulates  with  the 
disk  between  the  thirty-sixth  and  thirty-seventh  vertebra. 

Cervical  vertebrce. —  These  vertebrae  have  the  compressed  bodies  and  large  hoop-like  transverse 
processes  of  the  adult,  with  the  exception  of  the  first  in  which  the  transverse  process  is  reduced 
to  a  tubercle,  and  of  the  second  where  it  is  a  large  plate  perforated  by  a  rather  small  foramen. 
These  processes  converge  by  their  tips,  in  consequence  of  the  inclination  of  those  of  the  second 
and  third  vertebrae.  The  inclined  and  enlarged  transverse  process  of  the  axis  overhangs  that 
of  the  third  vertebra,  its  tip  lying  opposite  the  interval  between  the  transverse  processes  of  the 
third  and  fourth,  but  not  descending  actually  to  the  level  of  the  latter  vertebra.  The  process 
of  the  fourth  cervical  is  transverse  as  is  also  that  of  the  fifth.  In  comparison  with  B.  musculus 
(  =  physeter)1,  there  is  much  less  convergence  of  these  processes,  and  the  lower  ones  of  the  series 
do  not  ascend  as  in  that  species,  in  consequence  of  which  a  somewhat  greater  range  of  move- 
ment in  the  neck  may  perhaps  be  inferred  of  B.  borealis. 

The  costal  process  of  the  sixth  cervical  vertebra  is  reduced  to  a  small  nodule  of  cartilage, 
which  is  not  fused  with  the  centrum,  but  articulates  with  it,  and  within  a  narrow  range  is  mov- 
able upon  it.  The  condition  is  symmetrical.  The  seventh  cervical  vertebra  has  lost  its  costal 
process.  This  is  now  represented  by  the  upper  bar  of  the  so-called  bicipital  rib.  That  we  are 
dealing  here  with  a  structure  analogous  to  the  variant  cervical  rib  of  man  seems  certain.  The 
element  in  this  foetus  would  seem  to  represent  the  distal  portion  of  the  rib  beyond  its  tubercle, 
for  it  is  connected  by  ligament  to  the  true  transverse  process  of  the  seventh  cervical.  The 
proximal  portion,  the  neck  and  head,  are  absent. 

It  is  possible  to  find  in  the  great  size  of  the  vertebral  plexus  a  factor  in  the  interruption 
of  the  costal  processes  of  the  last  two  cervical  vertebrae.  This  large  plexus  has  expanded  in  the 
foramina  transversaria  of  the  third,  fourth  and  fifth  vertebrae,  reducing  the  transverse  processes 
to  slender  bars  of  cartilage.  That  this  may  be  a  real  factor  in  the  modification  of  these  parts 
and  not  simply  a  correlated  peculiarity,  is  borne  out  by  the  well  known  phenomenon  of  absorption 
of  cartilage  or  bone  under  pressure  from  blood  vessels.  At  the  root  of  the  neck,  the  vertebral 

1  Struthers,  J.     On  the  cervical  vertebrae  and  their  articulations  in  fin-whales.     Jour.  Anat.  and  Phys.,  Vol.  VII,  1872. 


486  SCHULTE,  SET  WHALE. 

venous  plexus  turns  ventrad  and  condensing  to  a  large  but  short  vertebral  vein  joins  the  superior 
intercostal  and  the  large  spinal  tap  to  form  the  posterior  thoracic  vein  of  Turner,  which  arches 
over  the  dome  of  the  pleura  to  the  vena  brachiocephalica.     The  confluence  of  these  vessels  occu- 
pies the  pyramidal  space  above  the  pleura  and  between  the  rectus  anticus  and  scalenus  muscles. 
In  the  dorsal  portion  of  this  space,  approximately  at  the  level  of  the  pleural  dome  projects  the 
neck  of  the  second  rib.     This  is  crossed  ventrally  by  the  superior  intercostal  vein,  which  meets 
the  vertebral  at  its  rostral  border.     The  interval  between  the  second  rib  and  the  costal  process 
of  the  fifth  cervical  vertebra,  on  account  of  the  shortening  of  this  region  of  the  spine,  is  small  and 
is  occupied  in  its  entirety  by  the  vertebral  plexus  as  it  turns  ventrad  to  its  debouchment,  the 
only  other  structures  present  being  the  vertebral  artery  and  the  very  large  stellate  ganglion 
of  the  sympathetic.     Had  the  costal  processes  in  this  region  persisted,  the  intervals  between  them 
would  have  been  entirely  inadequate  to  the  drainage  of  the  plexus.     Its  presence  therefore 
seems  to  have  modified  the  development  of  this  region  reducing  and  separating  from  the  vertebra 
the  costal  elements.     In  a  sense  this  argument  of  room  for  drainage  seems  to  be  borne  out  by  the 
conditions  in  B.  physeter  as  described  and  figured  by  Struthers,  where  the  requisite  space  is  gained, 
not  by  the  interruption  but  by  t.he  inclination  rostrad  of  the  costal  processes.     That  of  the  sixth 
cervical  is  in  B.  borealis  only  retarded  in  development,  for  it  may  form  a  complete  arch  in  the 
adult.     That  of   the  seventh  is  separated  from   its  vertebra,  losing  its  mesal  segment,  from 
tubercle  to  capitellum  while  its  remainder  hypertrophies  and  fuses  with  the  first  thoracic  rib. 
This  also  has  lost  its  proximal  segment  and  articulates  only  with  the  transverse  process. 

The  spinous  processes  of  the  atlas  and  axis  are  of  small  size,  in  fact  are  little  more  than 
tubercles;  those  of  the  remaining  vertebrae  increase  in  height  caudad.  They  are  compressed  from 
side  to  side,  blunt  and  almost  rectangular  at  their  summits;  none  of  them  have  a  pointed  profile. 
On  the  transverse  processes  dorsally  at  a  short  distance  laterad  of  the  prezygapophyses  are 
very  small  conical  processes,  better  marked  on  the  more  caudal  vertebra?,  which  give  origin, 
to  the  trachelo-occipital  muscle  and  supply  points  of  attachment  to  the  semispinalis  capitis. 
These  processes  are  well  shown  in  Andrews's  figures  of  the  adult  vertebrae  of  this  species.  In 
Struthers's  illustration  '  of  B.  physeter  they  appear  on  each  side  as  a  small  tubercle,  between 
what  he  designates  as  the  nerve  groove  stage  and  the  tubercular  stage  of  the  transverse 
process. 

The  atlas  is  less  massive  in  its  build  and  more  ringlike  in  form  than  that  of  the  adult.  This 
depends  upon  the  relatively  smaller  size  of  the  lateral  masses  and  the  enlargement  at  their  ex- 
pense of  the  ventral  portion  of  the  neural  canal  embraced  between  them,  which  in  the  fcetus 
exceeds  in  cross-section  the  region  occupied  by  the  spinal  cord  and  its  membranes.  The  sur- 
faces of  articulation  with  the  occipital  condyles  converge  ventrad  extending  well  upon  the 
ventral  arch  where  their  extremities  are  separated  by  an  interval  of  2  mm.  Their  mesal  margins 
are  distinctly  concave  and  of  a  curvature  almost  concentric  with  that  of  their  lateral  margins. 
Their  extremities  are  rather  pointed,  their  breadth  far  less  than  that  of  the  condyles.  Dorsally 
at  their  junction  with  the  dorsal  arch  there  is  a  deep  groove  for  the  vertebral  artery,  and  this 
groove  is  not  bridged  over  and  converted  into  a  foramen  as  in  the  adult.  The  spinous  process 
is  reduced  to  a  tubercle;  the  transverse  process  is  very  short,  blunt  and  imperf orate.  The 
ventral  arch  increases  in  sagittal  depth  towards  the  midline  and  here  its  caudal  margin  protrudes 
slightly  beyond  the  body  of  the  axis  to  give  attachment  to  the  longus  colli.  The  articular  sur- 


1  Struthers,  F.     Op.  cit.,  pi.  2,  fig.  iv. 


SCIirLTK,  SKI  WHALK.  -is? 

face  for  the  axis  is  narrower  than  in  the  adult.  Its  long  axis  is  dorso- ventral.  It  sends  upon 
the  ventral  arch  a  slender  prolongation,  which  fails  by  a  narrow  interval  of  meeting  its  fellow  of 
the  opposite  side. 

The  capsule  of  the  atlanto-occipital  articulation  is  very  strong  and  is  attached  round  the 
margin  of  the  articular  surface,  a  faint  groove  being  present  on  the  lateral  mass  for  its  reception. 
The  space  between  the  lateral  masses  entally  is  filled  with  strong  connective  tissue,  of  which  the 
bundles  are  for  the  greater  part  oriented  transversely  and  seem  therefore  to  represent  the  trans- 
verse ligament  of  the  atlas.  This  is  broad  and  thin  and  passes  us  Struthers  has  shown  rostral 
and  not  dorsal  to  the  odontoid  process.  Its  margins  are  concave;  between  the  ventral  one  and 
the  arch  of  the  atlas,  the  ligamentum  apicis  dentis  passes  to  its  insertion  on  the  basioccipital 
in  the  fossa  between  the  condyles  and  the  ventral  to  the  foramen  magnum.  In  cross  section 
this  ligament  appears  to  contain  a  cavity,  which  is  probably  related  to  the  degeneration  of  the 
notochord,  about  which  the  ligament  develops. 

Dimensions  of  (he  atlas. 

mm. 

Hreadtli  between  tips  of  transverse  processes 21 

I  torso-ventral  diameter 18 

I  )orso- ventral  diameter  of  neural  canal 12 

Dorso-ventral  diameter  of  its  dorsal  compartment 6 

Dorso-ventral  diameter  of  its  ventral  compartment 0 

Transverse  diameter  of  its  dorsal  compartment - 7 

Transverse  diameter  of  its  ventral  compartment 

Length  of  articular  surface  for  occipital 13 

Greatest  breadth  of  articular  surface  for  occipital 5 

Axis:  -  -  This  vertebra  is  characterized  by  the  large  size  of  its  transverse  processes,  which 
in  consequence  of  a  smaller  foramen  are  more  massive  than  those  of  the  succeeding  vertebrae. 
They  are  directed  obliquely  caudad  and  laterad  in  the  form  of  plates  with  rostral  and  caudal 
surfaces.  Their  extremities  are  broad  and  rounded  and  contrast  in  this  respect  with  the  more 
pointed  form  of  the  adult.  The  spinous  process  is  feebly  developed.  The  articular  surfaces 
for  the  atlas  are  concave  from  side  to  side,  dorso-ventrally  they  appear  flat.  Their  ventral 
extremities  are  not  confluent  but  are  separated  by  a  very  narrow  interval.  They  differ  from 
those  of  the  adult  chiefly  in  the  regularity  of  the  curve  of  their  lateral  contour.  The  space 
between  them  rises  very  slightly  in  a  low  cone,  the  odontoid  process.  Dorso-ventrally  the  axis 
measures  16.5  mm.,  transversely  27  mm.  The  spinal  canal  in  the  corresponding  diameters  is 
6  mm.  by  7  mm. 

Ribs:  —  There  are  thirteen  pairs  of  thoracic  ribs,  and  in  addition  a  well  developed  cervical 
rib  fused  with  the  first  of  the  thoracic  series.  The  thoracic  ribs  with  the  exception  of  the  first 
are  a  series  of  slender  bars  increasing  in  length  to  the  seventh  and  then  diminishing.  The  last, 
however,  is  not  greatly  reduced.  The  last  three  ribs  diverge  by  reason  of  the  increasing  obli- 
quity of  the  more  caudal  ones,,  so  that  the  corresponding  intercostal  spaces  broaden  ventrad; 
the  last  rib  makes  an  angle  of  something  under  45°  with  the  horizontal.  The  second  and  third 
ribs  have  well  developed  necks  and  heads,  the  latter  articulating  with  the  vertebral  centra; 
that  of  the  second  articulates  with  the  second  thoracic  vertebra  near  its  rostral  margin  impinging 
slightly  upon  the  preceding  intervertebral  disk.  The  head  of  the  third  rib  articulates  with  the 
disk  between  the  third  and  fourth  vertebrae,  touching  their  bodies  to  only  the  slightest  degree. 


488 


SCHULTE,  SEI  WHALE. 


The  fourth  rib  has  a  rudimentary  neck  and  head,  which  fails  to  reach  the  vertebrae.  The 
remaining  ribs  lack  these  parts  and  articulate  by  their  proximal  extremities  with  the  trans- 
verse processes.  The  lengths  of  the  ribs  are  given  in  the  following  table.  Tne  measurements 
were  taken  with  callipers  from  end  to  end. 


1. 

2 

3. 

4. 

5. 

6. 

7. 

8. 

9. 
10. 
11. 
12. 
13. 


mm. 
30 
45 
50.5 
52.5 
54.5 
57.5 
60.5 
58 
54.5 
51. 
46. 
45. 
35. 


The  first  rib,  as  has  been  said,  is  bicipital,  a  cervical  rib  being  fused  with  its  rostral  aspect. 
A  narrow  cleft,  diminishing  ventrad,  separates  the  two  portions  as  they  approach  the  spine, 

this  interval  has  a  length  of  12  mm.  It  is 
filled  with  muscle  of  the  same  orientation  and 
continuous  with  the  scalenus.  The  cervical 
rib  expands  proximad,  becoming  flattened 
rostro-caudad  and  articulating  with  the  trans- 
verse process  (dorsal  bar)  of  the  seventh  cervi- 
cal vertebra.  Ventrally  it  is  connected  with 
the  transverse  process  of  the  fifth  cervical  by 
ligament.  The  proximal  extremity  of  the  first 
thoracic  rib  is  also  flattened  and  expanded. 
It  articulates  with  the  transverse  process  of  the 
first  thoracic  vertebra.  In  both,  the  head  and 
neck  are  wanting.  The  condition  is  identical 
upon  the  two  sides. 

That  the  additional  element  in  this  fused 
rib  is  a  cervical  rib  is  shown  not  only  by  its 
topography  and  connections,  but  also  by  the 
absence  of  the  ventral  bar  (costal  process)  of 
the  transverse  process  of  the  seventh  cervical  vertebra. 

While  the  morphology  of  the  two-headed  rib  presents  no  especial  difficulties,  its  taxonomic 
value  has  been  the  subject  of  much  discussion.1  It  has  been  argued  that  as  the  cervical  rib  in 
man  is  a  variant,  so  it  is  also  in  Balcenoptera  borealis,  an  argument  evidently  wrong  in  principle, 
for  the  question  of  normal  vs.  variant  in  a  species  must  be  answered  by  establishing  with  a 


Fig.  8.  Sternum  and  first  rib.  1,  Sternum.  2,  Cervical  rib. 
3,  First  thoracic  rib.  4,  Sternohyoid.  5,  Sternomastoid.  6, 
Sternomandibularis.  7,  Pectoralis.  8,  Rectus.  9,  Obliquus  ext. 
10,  Scalenus. 


1  Turner,  W.  On  the  so-called  two-headed  ribs  in  whales  and  man.  Jour.  Anat.  and  Phys.,  Vol.  5,  1870-1871,  p.  349.  This  article 
is  useful  for  the  older  literature.  Also,  by  the  same  author,  the  transverse  processes  of  the  seventh  cervical  vertebra  in  Balcenoptera 
Sibaldii.  Jour.  Anat.  and  Phys.,  Vol.  5,  p. '382.  The  so-called  two-headed  ribs  in  whales  and  man.  Jour.  Anat.  and  Phys.,  Vol.  6. 
p.  445.  Cervical  ribs  and  so-called  bicipital  ribs  in  man,  in  relation  to  corresponding  structures  in  the  Cetacea.  Jour.  Anat.  and  Phys., 
Vol.  17,  p.  384. 


SCHULTE,  SEI  WHALE.  489 

sufficient  number  of  observations,  the  constancy  or  preponderating  frequency  in  that  given 
species  of  the  structure  in  question.  The  doubt  of  the  normality  of  the  cervical  rib  in  B.  borealis, 
is  only  such  as  is  incident  to  the  necessarily  limited  number  of  individuals  examined  of  an  animal 
so  difficult  to  procure. 

The  sternum. —  The  sternum  is  lozenge-shaped  with  produced  angles;  the  elongation  of 
the  caudal  one  is  much  less  than  in  Fischer's,1  or  even  Flower's  2  illustration  of  the  adult  bone. 
It  measures  13.5  mm.  in  breadth  by  11.5  mm.  in  length.  Its  caudal  margin  rests  against  the 
ventral  extremities  of  the  rib  of  the  first  pair,  and  the  short  caudal  process  is  inserted  between 
them.  It  is  joined  to  the  ribs  by  a  firm  connective  tissue,  without  the  presence  of  a  joint  cavity. 


THE  PECTORAL  LIMB. 

Scapula: — The  scapula  is  rather  low,  its  length  being  nearly  twice  its  breadth  (40  mm., 
22  mm.).  The  vertebral  border  presents  three  convexities  separated  by  slight  concavities. 
The  caudal  border  is  concave  near  the  neck,  slightly  convex  at  the  distal  limit  of  the  teres  origin, 
and  thence  nearly  straight  to  the  caudal  angle  which  is  rounded.  The  cephalic  border  is  slightly 
convex  as  far  ventrad  as  the  acromion,  and  in  this  part  of  its  course  beveled  and  separated  by 
a  low  ridge  from  the  dorsum.  As  this  ridge  defines  the  limit  of  the  supraspinalis  origin  it  is  taken 
to  represent  the  spine  of  the  scapula  and  the  beveled  margin  corresponds  to  the  supraspinous 
fossa.  The  acromion  is  very  long,  its  extremity  lying  vertically  below  the  cephalic  angle.  Its 
borders  dorsal  and  ventral  are  parallel;  its  tip  is  blunt;  only  its  base  is  ossified.  The  venter 
of  the  scapula  is  very  slightly  concave  at  its  junction  with  the  neck,  elsewhere  flat.  The  cora- 
coid  is  robust,  tapering  slightly  to  its  summit.  It  is  directed  cephalad  and  to  a  less  degree  ventrad 
and  mesad.  It  is  wholly  cartilaginous.  The  glenoid  fossa  is  deep  with  prominent  thin  margins. 
Its  shape  is  nearly  triangular  owing  to  the  marked  projection  of  its  dorsal  border  in  a  rounded 
angle.  The  articular  surface  is  almost  wholly  formed  by  the  scapula.  To  the  base  of  the  cora- 
coid  as  it  presents  in  the  joint-cavity  is  attached  a  strengthening  band  of  the  capsule,  visible 
from  within  the  joint  and  continuous  with  the  fibrous  bands  of  the  flexor  surface  of  the  humerus  - 
a  fact  which  fully  justifies  their  interpretation  as  bicipital  rudiments.  The  ossification  includes 
the  greater  portion  of  the  blade,  the  cephalic  and  caudal  borders  and  extends  into  the  neck 
and  the  base  of  the  acromion,  leaving  the  parts  adjacent  to  the  vertebral  margin  (suprascapula), 
the  glenoid  region,  and  the  whole  coracoid  still  cartilaginous.  The  surface  for  muscular  origin 
is  increased  by  two  strong  aponeuroses.  One  at  the  caudal  margin  stretches  across  the  concavity 
between  the  origin  of  the  teres  and  the  glenoid  margin  and  serves  as  an  intermuscular  septum 
between  this  muscle  and  the  subscapularis.  The  other  stretching  between  the  dorsal  margin 
of  the  acromion  and  the  ridge  representative  of  the  spine  increases  the  surface  of  origin  of  the 
supraspinatus  and  deltoid  muscles. 

Humerus. —  The  humerus  is  short  and  stout,  its  long  axis  oblique  from  the  shoulder  caudad, 
ventrad  and  slightly  laterad.  The  head  which  looks  chiefly  dorsad,  to  a  less  degree  mesad  and 
cephalad,  meets  the  shaft  at  an  obtuse  angle.  The  articular  surface  is  globular  except  that  it  is 

1  Fischer,  M.     Ce'tace'es  du  sud-ouest  de  la  France.     Actes  Soc.  Linn.  Bordeaux,  1881.     Quoted  in  Beddard,  F.  E.,  A  book  of  whales. 
New  York,  1900.     PI.  iii,  fig.  10a. 

1  Flower,  W.  H.     On  a  specimen  of  Rudolphi's  rorqual  taken  recently  on  the  Essex  coast.     P.  Z.  S.,  1883,  p.  513. 


490  SCHULTE,  SEI  WHALE. 

abruptly  planed  off  when  it  joins  the  flexor  surface  of  the  shaft,  so  that  here  it  rises  very  slightly 
above  the  level  of  this  surface,  from  which  it  is  separated  by  an  arched  margin.     The  articular 
surface  of  the  humerus  exceeds  that  of  the  glenoid  fossa  considerably  in  the  transverse  diameter, 
to  only  a  slight  degree  in  the  sagittal,  so  that  it  may  be  inferred  that  the  movements  of  ab-  and 
adduction  are  more  free  than  those  of  flexion  or  extension.     The  capsule  of  the  scapulo-humeral 
articulation  is  attached  close  to  the  margins  of  the  articular  surface,  the  neck  of  the  humerus 
being  extremely  short  and  marked  only  by  a  groove  between  the  head  and  radial  tuberosity 
in  which  the  capsule  is  attached.     This  tuberosity  juts  out  from  the  preaxial  border,  its  flexor 
and  extensor  surfaces  falling  into  the  level  of  the  corresponding  surfaces  of  the  shaft.     Proxi- 
mally  it  presents  a  quadrangular  surface  which  like  the  rest  of  the  tuberosity  is  rough  for  muscu- 
lar attachments.     Further  mesad,  close  to  the  articular  surface,  on  the  flexor  surface  and  not  at 
the  postaxial  border  is  a  second  rough  and  slightly  projecting  area  into  which  the  subscapularis 
muscle  is  inserted.     It  is  separated  from  the  radial  tuberosity  by  a  groove  which  lodges  the 
tendon  of  the  masto-humeralis.     The  shaft  is  oval  in  section  proximad  becoming  more  flattened 
towards  the  elbow.     The  margins  are  concave,  especially  the  postaxial.     The  extensor  surface 
is  convex,  the  flexor  rather  flat.     Distad  there  are  two  articular  surfaces  separated  by  a  low 
ridge  for  the  radius  and  ulna,  the  latter  being  considerably  the  larger.     Only  the  middle  third 
of  the  shaft  is  ossified  and  here  the  process  seems  less  in  degree  than  in  the  shafts  of  the  radius 
and  ulna.     The  length  of  the  humerus  is  14  mm.,  its  greatest  breadth  from  head  to  tuberosity 
is  8  mm.,  that  of  the  lower  extremity  is  7  mm.,  of  the  middle  of  the  shaft  5.5  mm.     The  junction 
of  the  humerus  with  the  bones  of  the  antibrachium  is  at  an  angle,  the  long  axis  of  the  humerus 
deviating  slightly  in  a  dorsal  direction  from  the  long  axis  of  the  limb  so  that  at  this  point  both 
the  preaxial  margin  and  flexor  surface  are  slightly  concave. 

Radius: —  The  radius  is  the  stouter  of  the  bones  of  the  antibrachium.  It  is  slightly  flattened 
dorso-ventrally  and  the  shaft  presents  a  marked  curvature,  convex  preaxially  in  the  middle  and 
curved  in  the  opposite  sense  at  the  two  extremities.  While  occupying  a  smaller  area  than  the  ulna 
upon  the  humerus,  at  the  carpus  its  surface  is  the  greater,  articulating  with  the  radiale  and  the 
whole  of  the  intermedium.  The  shaft  is  ossified,  the  extremities  cartilaginous.  The  total  length 
is  18  mm.,  the  proximal  cartilage  3  mm.,  the  distal  4.5  mm.,  the  remaining  10.5  mm.  being  com- 
prised in  the  ossified  diaphysis. 

Ulna: — The  ulna  is  longer  and  more  slender  than  the  radius.  Its  proximal  extremity  is 
prolonged  upon  the  postaxial  border  of  the  humerus  thus  enlarging  their  articular  surface.  This 
is  on  the  whole  concave  comprising  a  smaller  vertical  and  larger  transverse  portion,  the  two 
meeting  at  a  rounded  angle.  In  this  region  the  ulna  is  dorso-ventrally  flattened.  Here  it  is 
joined  by  the  very  large  olecranon  cartilage  which  projects  in  a  dorsicaudal  direction.  It  is  com- 
pressed, broadens  towards  its  free  extremity  which  is  convex  giving  the  whole  cartilage  much 
the  shape  of  an  ax-head.  The  shaft  of  the  ulna  is  rounded  and  ossified.  Its  carpal  extremity 
again  expands  slightly  and  is  flattened.  It  articulates  with  the  ulnare  and  with  the  pisiform. 
Its  length  is  22.5  mm.,  of  which  10.5  mm.  is  occupied  by  the  ossification  of  the  diaphysis, 
7  mm.  by  the  proximal  cartilage,.  5  mm.  by  the  distal,  thus  corresponding  closely  with  the 
radius  in  the  length  of  diaphysis  and  distal  cartilage. 

Carpus: —  The  carpus  is  wholly  cartilaginous.  In  the  first  row  there  are  four  elements, 
radiale  and  intermedium  articulating  with  the  radius,  ulnare  and  pisiform  articulating  with 
ulna,  which  is  partially  united  with  the  ulnare.  The  carpalia  are  much  reduced.  Carpale 


SCHn.TK,  SKI  WIIALK. 


Fig.  9.  Section  of  carpus.  Camera  lucicla  tracing.  1, 
Radius.  2,  Ulna.  3,  Pisiform.  4,  Radialo.  5,  Intermedium, 
6,  Ulnare.  7,  Carpale  1.  8,  Carpalia  2  and  3.  9-12,  Meta- 
carpalia  2-5. 


I,1  is  represented  by  a  very  minute  cartilage  at  the  preaxial  border  of  the  metacarpus  inter- 
posed between  the  radiale  and  the  metacarpal  of 
digit  II,  with  which  latter  it  is  partially  fused. 
A  second  element  of  this  row  is  of  larger  size. 
Proximad  it  articulates  with  radiale  and  inter- 
medium, distad  with  the  metacarpalia  of  digits  II 
and  III,  by  its  postaxial  border  with  the  fourth 
metacarpal.  This  element  is  imperfectly  separate 
from  metacarpale  II.  It  probably  represents  the 
fused  carpalia  II  and  III. 

I)i(/itx: —  In  all  the  metacarpalia  are  assimi- 
lated in  form  to  the  phalanges.  Those  of  digits 
IV  and  V  articulate  with  elements  of  the  first  row 
of  the  carpus;  metacarpale  IV  with  the  interme- 
dium and  ulnare,  metacarpale  V  with  the  ulnare 
and  pisiform.  There  is  no  sign  of  a  first  digit. 
The  number  of  elements  in  each  digit,  the  metacarpal  included,  is  as  follows:  II-4;  III-7;  IV-7; 
V-4. 

Pelvis: —  The  os  innominatum  is  embedded  in  the  junction  of  the  ischio-caudalis  and  the 
rectus  muscles,  so  that  only  the  pubic  region  is  exposed  in  ventral  view,  and  this  is  situated 
close  to  the  lateral  margin  of  the  neuro-vascular  foramen  in  the  latter  muscle.  The  extremities 

of  the  ilia  are  connected  by  ligaments,  the  prepelvic 
bands  of  Struthers,2  to  the  termination  of  the  linea 
alba.  In  shape  the  -innominate  bone  resembles  that 
of  B.  rostrata  figured  by  Eschricht 3  more  closely  than 
that  of  B.  borealis  in  Struthers'  illustration.4  The 
ilium  is  slender  and  rod-like,  the  ischium  expanded 
and  dorso-ventrally  flattened.  Entally  the  two  por- 
tions fall  into  one  continuous  curve,  while  ectally  the 
region  of  junction  is  marked  by  the  small  projection  of 
the  pubis.  The  total  length  of  the  cartilage  is  9.5 
mm.;  the  breadth  of  the  ischium  is  2  mm.,  that  of  the 
ilium  about  half  as  much.  The  ischia  of  the  two  sides 
are  separated  by  an  interval  of  10  mm.,  the  tips  of  the  ilia  by  a  distance  of  6  mm.  There  was 
no  femoral  cartilage. 


Fig.  10.  Pelvic  rudiments.  2X  nat.  size.  1,  Ilium. 
2,  Pubes.  3,  Ischium.  4,  Insertion  of  rectus  abdominis. 
5,  Origin  of  ischio-caudalis.  6,  Origin  of  ischio-cavernosus. 


'  Leboucq,  H.  Recherches  sur  la  morphologic  de  la  main  chez  les  mammifercs  inarms,  Pinnipedes,  Sireniens,  Cetaces.  Arch,  de 
Biol .,  T.  IX.  '  1889,  p.  571.  Cf.  pi.  xl,  figs.  50-52. 

'-  Struthers,  John.  On  the  rudimentary  hind  limb  of  a-great  fin-whale  (Balasnoptera  muscul  13)  m  comparison  with  those  of  the  hump- 
back and  the  Greenland  right-whale.  Jour.  Anat.  and  Phys,  N.  S.,  Vol.  XXVII,  1893,  p.  293. 

•  Eschricht,  D.  F.  Untersuchungen  iiber  die  nordischen  Waltiere,  I.  fig.  42.  Cf.  Abel,  O.  Die  Morphologie  der  Huftbeinrudimente 
der  Cetaceen.  Denkschr.  der  Akad.  der  Wiss,  Math.-Naturw.  Klasse,  Bd.  81 . 

4  Id.  Plate  XX,  Wien  1908,  Fig.  7. 


492  SCHULTE,  SEI  WHALE. 


THE  EAR. 

BY  JOHN  D.  KERNAN,  JR. 
(Plate  LVII,  fig.  3). 

External  auditory  meatus:  —  The  external  orifice  of  the  auditory  meatus  is  a  minute  opening 
situated  24  mm.  caudal  to  the  center  of  the  eye  and  9  mm.  dorsal.  No  auricular  cartilage  could 
be  found  on  gross  examination,  which  alone  was  possible,  nor  were  the  muscles  described  by 
Hanke1  definitely  ascertained  to  be  present. 

The  auditory  meatus  itself  passes  rostro-mesad  in  a  groove  in  the  squamosum,  as  described 
by  various  authors.  In  the  lateral  part  of  its  course  it  is  an  exceedingly  small  tube.  Mesally 
it  expands  like  the  mouth  of  a  speaking  trumpet  and  the  ental  extremity  is  attached  to  the 
concave  edge  of  the  tympanum,  and  to  that  part  of  the  squamosum  which  completes  the  tym- 
panic ring.  The  lumen  of  the  meatus  is  laterally  circular.  The  mesal  expansion  takes  place 
in  a  horizontal  axis,  caudo-rostrad,  and  scarcely  at  all  vertically.  Thus  the  inner  extremity  of 
the  tube  presents  on  cross  section  the  appearance  of  a  horizontal  slit  with  dorsal  and  ventral 
walls  almost  in  contact.  The  plug  of  cerumenous  material  described  by  Lillie  2  and  Hanke, 
was  not  present. 

The  membrana  tympani  is  elliptical  with  the  long  axis  pointing  rostro-mesad,  thus  con- 
tinuing the  direction  of  the  auditory  meatus.  The  plane  of  the  membrane  is  horizontal,  so  that 
in  place  of  forming  an  inner  wall  for  the  meatal  canal,  such  as  is  found  ordinarily  in  mammals, 
the  membrana  forms  in  reality  part  of  the  roof.  The  inner  extremity  of  the  canal  is  formed  by 
the  meeting  of  the  dorsal  and  ventral  walls  at  their  joint  attachment  to  the  concave  edge  of  the  os 
tympanicum.  The  extreme  horizontal  position  of  the  membrana  agrees  with  the  basal  position 
of  the  whole  auditory  apparatus  as  found  in  Balcenoptera  (van  Kampen).3  The  circumference 
of  the  membrana  is  attached  to  the  sharp,  concave  outer  margin  of  the  os  tympanicum,  and  to 
the  squamosum  where  the  circle  of  the  tympanic  is  incomplete.  No  distinction  can  be  drawn 
between  pars  tensa  and  pars  flaccida. 

From  the  description  of  the  membrana  tympani  thus  far  given  it  will  be  seen  that  at  this 
stage  it  is  typically  mammalian,  that  is  a  thin,  oval  membrane,  slightly  concave  toward  the 
inner  surface,  attached  by  its  margin  to  the  tympanic  ring.  There  is  as  yet  no  evidence  of  the 
finger-like  projection  of  the  membrane  outward  into  the  lumen  of  the  external  meatus  found  in 
the  adult  (Beauregard)4  nor  even  any  indication  of  its  approaching  formation  as  found  by 
Hanke  in  a  somewhat  older  fcetus  of  B.  musculus. 

In  one  important  respect  the  membrane  differs  from  that  of  other  mammals;  namely, 
in  its  relation  to  the  malleus.  From  this  structure  it  is  separated  by  a  considerable  space,  the 
membrane  forming  part  of  the  ventral  wall,  the  malleus  lying  close  to  the  dorsal  wall  of  the 
tympanic  cavity.  The  space  between  the  two,  which  is  triangular,  is  occupied  by  a  fold  of 
tissue  formed  from  the  membrane  itself.  From  the  tip  of  the  manubrium  mallei  to  the  inner 


1  Hanke,  H.     Ein  Beitriige  zur  Kenntnis  der  Anatomie  des  ailsseren  und  mittleren  Ohres  der  Bartenwall.     Jenaische  Zeitschrift 
fur  Xatur  Wissenschaft,  1914. 

2  Lillie.     On  the  Anatomy  and  Biology  of  the  larger  Cetacea.     Proc.  Zool.  Soc.  London,  Vol.  II,  1910. 

3  v.  Kampen,  P.  N.     Die  Tympanalgegend  des  Saugetierschadels.     Morph.  Jahrb.,  Bd.  XXXIV,  Hefte  3  u.  4,  1905. 

4  Beauregard,  H.     Recherches  sur  1'Appareil  Auditif  chez  les  Mammiferes.     Jour,  de  1'Anat.  et  de  la  Phys.,  An.  29-30,  1893-4. 


SCIU'LTE,  SET  AVHALE.  493 

surface  of  the  membrana  this  fold  forms  a  free  edge,  which  is  the  base  of  the  triangle.  The 
apex  is  at  the  outer  border  of  the  tympanic  cavity  where  malleus  and  membrana  approach  one 
another  though  not  in  contact.  The  sides  of  the  triangle  lie  along  the  attachment  of  the  fold 
to  malleus  and  membrana  respectively.  This  attachment  of  malleus  to  the  membrana  tympani 
corresponds  to  that  found  in  adults  of  this  species,  except  that  in  them  the  fold  is  greatly  elon- 
gated, owing  to  the  outward  projection  of  the  membrane. 

Cavum  tijnt/>(ini:  -  -  The  cavum  tympani  is  a  bowl  shaped  cavity,  having  dorsal  and  ventral 
walls  which  meet  in  a  sharp  angle  at  their  margins.  The  ventral  wall  contains  in  the  lateral 
area  the  membrana  tympani,  surrounded  by  the  crescentic  os  tympanicum.  The  rest  of  the 
ventral  wall  is  made  up  of  the  fibrous  bulla  which  fills  in  the  space  between  os  tympanicum  and 
the  marginal  attachment  of  the  bulla. 

The  dorsal  wall  of  the  tympanic  cavity  is  made  up  of  otic  capsule  centrally  placed,  and 
circumferentially  of  a  ring  of  fibrous  tissue  which  connects  the  petrosum  to  the  surrounding 
bones.  As  it  presents  itself  after  removal  of  the  os  tympanicum  and  bulla,  it  is  seen  to  be  cov- 
ered by  a  layer  of  thick  tissue  which  completely  conceals  the  underlying  cartilage  and  almost 
fills  the  cavity.  In  the  outer  area  of  the  cavity  this  structure  throws  folds  about  the  ossicles, 
and  only  on  its  removal  can  they  be  examined.  The  formation  of  this  tissue  shows  it  to  be  of  a 
cavernous  nature  (Beauregard)  and  its  function  is  variously  stated  as  hydrostatic  or  auditory. 
Tuba  auditiva:  -  -  The  tuba  auditiva  passes  from  the  choana  laterad  between  hamular 
and  vaginal  processes  of  the  internal  pterygoid  and  penetrates  the  wall  of  the  bulla  obliquely. 
Its  entrance  into  the  tympanic  cavity  is  at  the  rostral  circumference  of  the  same,  in  the  angle 
formed  by  the  meeting  of  ventral  and  dorsal  walls.  The  opening  is  a  crescentic  slit  capable  of 
valve-like  closure.  The  tube  is  very  short,  merely  an  oblique  passage  through  the  fibrous  wall 
of  the  bulla.  The  expansion  of  its  distal  end  into  the  scaphoid  fossa  as  found  in  the  adult  is  not 
yet  indicated. 

Ossicula  auditus:  -  -  The  ossicles  are  typically  mammalian  in  their  arrangement.  Meckel's 
cartilage  passes  beneath  the  edge  of  the  tympanic  bulla,  caudad  and  slightly  dorso-laterad, 
closely  roofed  over  by  the  tegmen  tympani.  Mesad  to  its  shaft  is  the  belly  and  tendon  of  the 
tensor  tympani  muscle.  Within  the  tympanic  cavity,  the  cartilage  expands  into  a  fairly  large 
caput  mallei,  and  forms  a  mesal  projection,  the  manubrium,  to  the  base  of  which  is  attached  the 
tensor  tympani.  A  groove  in  its  surface  completely  encircles  the  caput,  close  to  the  edge  of 
the  articulation  with  the  incus.  The  border  itself  expands,  thus  increasing  the  depth  of  the 
groove. 

The  incus  has  a  triradiate  form.  On  the  well  developed  body  is  a  saddle-shaped  articular 
surface  for  the  malleus.  The  processus  brevis  is  stout  and  of  large  size.  Its  extremity  is  in 
contact  with  the  crista  parotica,  to  which  it  is  firmly  attached  by  a  ligament.  The  processus 
longus,  which  actually  is  shorter  than  the  brevis,  is  also  bulky  in  form.  It  is  directed  ventrad 
to  articulate  through  an  os  lenticulare  with  the  apex  of  the  arch  of  the  stapes. 

The  stapes  which  is  lodged  in  a  deep  fossula,  does  not  fill  with  its  foot  plate  the  large  fenestra, 
but  is  united  to  its  circumference  by  a  rather  wide  annular  ligament.  The  bone  closely  agrees 
with  the  adult  form;  its  arch  is  high  and  narrow,  the  limbs  thick,  the  foramen  small. 

Capsula  otica:  —  The  otic  capsule,  in  contrast  to  its  relatively  small  size  in  the  adult,  is  here 
a  large  cartilage  forming  a  considerable  portion  of  the  floor  and  lateral  wall  of  the  posterior 
fossa. 

Caudad  the  capsule  is  in -contact  with  the  exoccipital,  a  thick  layer  of  perichondrium  being 


494  SCHULTE,  SET  WHALE. 

interposed.  The  line  of  union  is  interrupted  by  the  opening  of  the  jugular  foramen.  Mesally, 
the  capsule  extends  under  the  basi-occipital  and  basi-sphenoid,  in  such  a  way  as  greatly  to  nar- 
row the  ventral  surface  of  these  structures  as  compared  to  the  dorsal.  Although  the  contact 
is  intimate  there  is  no  real  union  of  substance,  except  at  the  most  rostral  part  of  the  line,  where 
there  is  found  the  broad  basi-capsular  commissure  already  mentioned  in  the  description  of  the 
cranial  cavity  as  a  whole.  It  should  be  noted  that  this  commissure  does  not  affect  the  whole 
thickness  of  the  apposed  structures,  but  is  merely  a  thin  shell  of  cartilage  joining  their  ental 
edges.  So  that  here  also  the  basi-capsular  fissure  is  all  but  complete. 

DeBurlet  in  a  104  mm.  embryo  of  B.  rostrata  ( =  acuto-rostrata) ,  found  five  commissures 
present  in  the  course  of  the  basi-capsular  fissure.  In  each  case  the  union  of  substance  involved 
only  the  ental  surface,  the  fissure  being  deep  and  continuous  in  ectal  view.  On  the  basis  of  a 
single  embryo  deBurlet  found  himself  unable  to  decide  whether  the  union  between  basal  plate 
and  otic  capsule  was  in  process  of  formation  or  of  resolution,  inclining  to  the  latter  view,  because 
of  the  freedom  of  the  periotic  in  the  adult,  an  opinion  which  receives  support  from  the  further 
reduction  of  the  commissures  in  this  older  foetus. 

Rostrad  the  otic  capsule  enters  into  the  border  of  the  fenestra  sphenoparietalis.  Here  its 
pole  is  received  into  a  concavity  of  the  external  pterygoid,1  which  on  its  lateral  aspect  is  drawn 
•out  into  a  stout  conical  process  under  cover  of  a  process  of  the  squamosal,  which  forms  the  mesal 
boundary  of  the  foramen  ovale  and  in  its  position  and  relations  evidently  corresponds  to  the 
processus  falciformis  of  Eschricht 2  and  Beauregard.  The  process  of  the  pterygoid  is  of  late 
development,  for  it  is  not  represented  in  deBurlet's  model. 

In  the  lateral  wall  of  the  cranium,  the  capsule  is  largely  under  cover  of  the  squamosal,  a 
small  oval  area  alone  appearing  in  the  interval  between  this  bone  and  the  exoccipital.  In  the 
natural  condition  of  the  parts,  this  surface  is  covered  by  a  thick  connective  tissue,  which  further 
closes  the  gap  above  the  capsule  between  the  exoccipital,  the  squamosal  and  the  parietal. 
While  this  area  corresponds  in  a  general  way  to  the  elongated  mastoid  of  the  adult,  it  is  to  be 
noted,  that  in  this  foetus,  the  relief  of  the  posterior  semicircular  canal  is  visible  on  the  surface 
and  the  definitive  mastoid  is  as  yet  barely  indicated. 

Under  cover  of  the  squamosal,  the  otic  capsule  still  retains  its  continuity  with  the  primitive 
cartilaginous  lateral  wall,  a  well  marked  commissura  orbitoparietalis,  extending  as  a  horizontal 
strip  from  the  ala  orbitalis  to  the  capsule,  which  it  joins  at  the  origin  of  the  commissura  prae- 
facialis. 

The  ventral  surface  of  the  capsula  otica  is  concealed  by  the  fibrous  auditory  bulla,  in  the 
substance  of  which  the  tympanic  is  embedded.  As  in  other  mammalian  chondrocrania,  when, 
as  yet  in  this  region,  ossification  has  not  begun,  two  portions  of  the  otic  capsule  are  dis- 
tinguishable, the  pars  canalicularis  and  pars  cochlearis,  of  which  the  latter  is  remarkable  for  its 
disproportionately  large  size. 

Pars  cochlearis:  -  -  The  pars  cochlearis  has  the  form  of  a  circular  disc  with  a  slightly  concave 
ental  surface,  and  convex  ectal  surface.  The  axis  about  which  the  coils  of  the  cochlea  turn  is 
almost  vertical,  pointing  from  above  downward  and  slightly  outward.  This  causes  the  surfaces 
to  face  dorsad  and  ventrad.  The  vertical  direction  of  the  cochlear  axis  is  an  indication  of  the 

1  Beauregard.     Journal  de  1'Anatomie  et  de  la  Physiologic,  V.  29,  1893. 

*  Eschricht,  D.  F.,  og  Reinhardt,  J.     Om.  Nordnvalen  (Balaena  mysticetus)  Klg.  Danskevidensk.  Selek.  Skriftet  (5),  nat.  og  math. 
Afd.,  V. 


SCHULTE,  SKI  WHALE.  495 

extent  to  which  the  displacement  of  the  otic  capsule  from  its  primitive  position  in  the  side  wall 
of  the  cranium,  toward  a  basal  position  has  proceeded  in  Balcenoptera.  These  surfaces  are 
demarcated  by  the  convex  edge  of  the  first  turn  of  the  cochlea,  except  dorso-laterally,  where 
the  border  is  interrupted  by  the  junction  with  the  pars  canalicularis.  In  this  region  the  dorsal 
surface  passes  without  interruption  into  the  mesal  surface  of  the  pars  canalicularis.  Not  all 
the  dorsal  surface  appears  in  the  cranial  cavity.  It  will  be  recalled  that  the  cochlea  dips  under 
the  basi-occipital  and  basi-sphenoid,  and  this  causes  a  crescentic  shaped  area  mesally  and 
rostrally,  to  be  shut  off  from  the  cranial  cavity  by  that  overhang  of  the  basal  plate,  designated  by 
deBurlet  as  lamina  supracochlearis.  An  additional  portion  of  the  dorsal  surface  is  outside  of 
the  cranial  cavity,  owing  to  the  attachment  of  the  dura  to  the  prefacial  commissure  and  to  the 
ridge  on  the  surface  leading  from  it  rostro-mesad.  Laterad  to  this  ridge  is  an  area  which  forms 
the  floor  of  the  cavum  supracochleare.1  In  the  center  of  the  cranial  surface  is  a  large  circular 
opening,  the  foramen  acusticum.  Laterad  to  this  opening,  divided  from  it  by  a  sharp  ridge, 
is  the  ental  opening  of  the  facial  canal.  Caudal  to  it  is  a  ridge  which  has  its  origin  upon 
the  mesal  surface  of  the  pars  canalicularis,  and  passes  ventro-mesad  'upon  the  pars  cochlearis, 
diminishing  in  prominence  as  it  descends.  Caudal  to  this  ridge  is  a  large  opening  in  the  carti- 
lage which  has  the  shape  of  a  figure  eight,  and  extends  to  the  edge  of  the  surface.  This  opening 
is  the  combined  ductus  perilymphaticus  and  fenestra  rotunda.  Their  approaching  separation 
is  indicated  by  the  shape  of  the  orifice. 

The  ventral  surface  of  the  pars  cochlearis  is  entirely  hidden  from  view  by  the  tympanic 
bulla.  Upon  removal  of  this  it  is  seen  to  be  convex,  and  to  give  indication  in  the  form  of  alter- 
nating depressions  and  elevations  of  the  cochlear  turns  within  the  capsule.  Dorso-lateral  there 
is  a  deep  depression  in  the  surface.  In  this  depression  is  the  fenestra  ovalis  partially  filled  by 
the  foot  plate  of  the  stapes.  Caudad  to  this  depression  the  surface  is  raised  to  form  the 
promontory  which  intervenes  between  the  fenestrae.  The  dorso-lateral  edge  of  the  depression 
presents  a  ridge  which  marks  the  situation  of  the  facial  canal.  Above  the  facial  ridge,  the 
surface  meets  the  ventral  surface  of  the  overhanging  pars  canalicularis. 

Pars  canalicularis:  -  -  The  pars  canalicularis  has  four  surfaces,  a  ventral  entering  into  the 
tympanic  cavity,  a  rostro-mesal,  caudo-mesal,  lateral,  and  two  extremities,  caudal  and  rostral. 
The  rostro-mesal  surface  joins  smoothly  the  dorsal  surface  of  the  pars  cochlearis,  facing  only 
slightly  more  mesad  than  the  latter.  The  line  of  demarcation  can  be  drawn  from  the  facial 
canal  to  the  foramen  perilymphaticus.  The  surface  is  bounded  caudally  by  a  ridge  which  marks 
the  line  of  the  crus  commune  of  the  vertical  semicircular  canals,  and  which  has  already  been 
described  as  forming  a  ridge  upon  the  dorsal  surface  of  the  pars  cochlearis.  Upon  this  ridge  is 
seen  a  slit  like  opening,  from  which  extends  upward  a  shallow  groove.  This  slit  is  the  orifice 
for  the  ductus  endolymphaticus  and  the  groove  lodges  its  intracranial  portion.  The  surface  is 
framed  rostrally  and  laterally  by  the  arching  superior  semicircular  canal,  and  is  hollowed  to 
make  a  well  marked  subarcuate  fossa. 

The  caudo-mesal  surface  is  bounded  rostrally  by  the  crus  commune,  ventrally  by  the  large 
common  opening  of  the  ductus  perilymphaticus  and  fenestra  rotunda,  and  for  the  rest  of  its 
boundary  has  the  ridge  marking  the  course  of  the  posterior  semicircular  canal.  It  shows  a  slight 
depression  bordering  on  the  crus  communis,  which  may  indicate  a  posterior  subarcuate  fossa 

1  Voit.     Das  Primordial  cranium  dps  Kaninchens  Anat.  Hefte,  Bd.  38,  1909. 


490  SCHULTE,  SEI  WHAIJv 

such  as  Voit  found  in  the  rabbit.     The  rest  of  the  surface  shows  a  vertical  ridge  which  renders 
it  convex  latero-mesad. 

The  lateral  surface  has  as  its  boundaries,  dorsally  the  arch  formed  by  the  vertical  semi- 
circular canals,  and  ventrally  the  line  of  the  external  canal.  The  dorsal  boundary  is  thus  cres- 
centic  and  meets  the  ventral  edge  at  either  extremity.  The  ventral  edge,  rostrally  begins  at 
the  caudal  extremity  of  the  prefacial  commissure,  and  caudally  ends  at  the  tip  of  the  processus 
mastoideus,  at  the  origin  of  the  hyoid  bar.  This  marks  the  caudal' extremity  of  the  crista  paro- 
tica,  which  is  the  surface  relief  of  the  external  semicircular  canal.  Rostrad  to  the  canal  the 
border  serves  for  the  attachment  of  the  tegmen  tympani. 

The  lateral  surface,  having  the  boundaries  described  above  is  roughly  triangular,  each  side 
of  the  triangle  being  formed  by  a  semicircular  canal.  As  a  whole  it  is  convex,  due  to  the  pro- 
jection of  that  mass  of  cartilage  known  as  the  "massa  angularis."  1 

The  caudal  portion  of  the  surface,  which  shows  in  relief  the  underlying  posterior  semicir- 
cular canal  appears  upon  the  ectal  aspect  of  the  skull  between  exoccipital  and  squamosum. 
This  area  corresponds  in  its  position  to  the  adult  mastoid,  though  there  is  as  yet  no  indication 
of  the  definitive  mastoid. 

The  ventral  surface  of  the  pars  canalicularis  is  triangular,  the  apex  pointing  mesad.  The 
inner  half  of  the  surface  rests  on  the  pars  cochlearis,  and  there  is  an  intimate  union  of  their 
substance.  The  lateral  portion  of  the  surface  forms  the  roof  of  the  middle  ear  and  is  in  relation 
to  the  structures  contained  in  it.  The  base  of  the  triangle,  which  is  placed  laterad,  corresponds 
with  the  inferior  border  of  the  lateral  surface,  already  described. 

The  surfaces  narrow  at  either  extremity  as  do  those  of  a  triangular  pyramid.  Each  apex 
thus  formed  has  attached  to  it  a  cartilaginous  process.  The  caudal  of  these  is  the  hyoid  bar. 
From  this  region  is  eventually  developed  the  mastoid  process.  The  rostral  prolongation  extends 
to  the  pars  cochlearis,  roofing  over  the  primitive  facial  canal,  and  thus  forming  the  commissura 
prsefacialis. 

Canalis  facialis:  -  -  The  facial  nerve  passes  laterad,  reaching  the  ental  opening  of  the  facial 
canal  by  crossing  over  a  prominent  ridge  of  cartilage  which  divides  it  from  the  foramen  acusticum. 
The  two  apertures  for  the  facial  and  acoustic  nerves  are  surrounded  by  a  fairly  well  marked 
cartilaginous  rim.  Thus  is  delimited  the  porus  acusticus  internus.  At  the  ectal  end  of  the 
primitive  facial  canal,  the  nerve  lies  under  the  tegmen  tympani  entirely  concealed  from  view. 
The  hiatus  Fallopii  is  represented  by  a  slit  in  the  line  of  apposition  of  the  tegmen  tympani  to 
the  ectal  surface  of  the  pars  cochlearis.  Beneath  the  cover  of  the  tegmen  tympani  the  nerve 
turns  sharply  caudad.  In  its  course  above  the  fenestra  ovalis  it  lies  in  a  closed  canal  below  the 
crista  parotica.  Turning  ventrad  in  this  canal  it  appears  at  the  caudal  apex  of  the  pars  canali- 
cularis, mesal  to  the  hyoid  cartilage. 

Tegmen  tympani:  -  -  The  tegmen  tympani  is  a  quadrangular  plate  of  cartilage,  taking 
origin  by  its  caudo-dorsal  border  from  the  pars  canalicularis.  At  its  point  of  origin  it  covers 
the  angle  formed  by  the  meeting  of  the  anterior  and  external  semicircular  canals.  Its  convex 
ectal  surface  is  continuous  with  the  lateral  surface  of  the  pars  canalicularis.  The  ental  surface 
roofs  in  the  tympanic  cavity,  and  conceals  from  view  the  outer  end  of  the  primitive  facial  canal 
and  its  continuation  to  the  point  where  it  meets  the  crista  parotica.  To  the  rostro-dorsal 


1  Macklin,  C.  C.     The  skull  of  a  human  foetus  of  40  mm.     Am.  Jour.  Anat,  Vol.  XVI,  1914. 


SCHULTE,  SEI  WHALE.  407 

border  is  attached  the  ventral  border  of  the  parietal  plate  in  the  region  from  which  springs  the 
orbito-parietal  commissure.  The  rostral  extremity  of  this  border  is  in  relation  to  the  tip  of  the 
external  pterygoid  to  which  it  is  firmly  united  by  fibrous  tissue.  The  caudo-ventral  border 
forms  a  free  edge  overhanging  the  proximal  portion  of  the  shaft  of  Meckel's  cartilage  and  the 
ossicles  of  the  middle  ear.  At  its  caudal  extremity  it  meets  at  an  obtuse  angle  the  crista  paro- 
tica.  The  rostro-ventral  border  is  also  free,  and  is  in  contact  by  one  extremity  with  the  pre- 
facial  commissure,  by  the  other  with  the  shaft  of  Meckel's  cartilage. 

The  tegmen  tympani  is  related  by  its  ectal  surface  to  the  squamosal  by  its  ental  surface 
to  the  cavum  tympani  and  the  otic  capsule,  filling  in  like  a  wedge  the  space  between  the  two. 


498  SCHTJLTE,  SEI  WHALE. 


ILLUSTRATIONS. 

PLATES. 
Plate  XLIII. 

Fig.  1.     Superficial  dissection  exposing  panniculus. 
Fig.  2.     Musculature  of  ventral  pouch. 

Plate  XLIV. 

Fig.  1 .     Dissection  of  musculature  of  ventral  pouch  and  the  sternomandibularis. 

Fig.  2.     Superficial  muscles  of  face,  hyoid  musculature,  muscles  of  flipper,  of  neck  and  of  intermandibular  region. 

Plate  XLV. 

Fig.  1.    Musculature  of  flipper,  mesal  view. 

Fig.  2.     Skeleton  of  flipper,  mesal  view,  showing  attachments  of  muscles. 

Plate  XLVI. 

Fig.  1.     Skeleton  of  flipper,  lateral  view,  showing  attachments  of  muscles. 
Fig.  2.     Suprahyoid  and  infrahyoid  muscles. 

Plate  XLVII. 

Fig.  1 .     Deep  muscles  of  the  thorax  and  abdomen,  dorsal  musculature. 
Fig.  2.     Situs  viscerum,  and  hypaxial  muscle  of  pedicle. 

Plate  XLVIII. 

Fig.  1.    Thoracic,  abdominal  and  pelvic  muscles. 

Fig.  2.     Suboccipital  muscles. 

Fig.  3.     Hypaxial  muscles  of  neck  and  thorax,  pterygoid  muscles. 

Plate  XLIX. 

Fig.  1.     Tongue,  pharynx  and  larynx. 

Fig.  2.     Base  and  diaphragmatic  surface  of  heart. 

Fig.  3.     Cavities  of  the  atria. 

Plate  L. 

Fig.  1 .     Thoracic  viscera,  ventral  view. 

Fig.  2.     Thoracic  viscera,  ventral  view,  the  heart  and  great  veins  removed. 

Plate  LI. 

Fig.  1.     Ventral  view  of  uro-genital  apparatus  in  situ. 
Fig.  2.     Jejuno-ileum,  ventral  view. 
Fig.  3.     Jejuno-ileum,  dorsal  view. 

Plate  LII. 

Fig.  1.  Ventral  view  of  stomach,  duodenum  and  arch  of  colon. 

Fig.  2.  Interior  of  stomach. 

Fig.  3.  Dorsal  view  of  preumbilical  visceral  complex. 

Fig.  4.  Dorsal  view  of  liver. 


SCHULTE,  SEI  WHALE.  499 

Plate  LIIl. 

Fig.  1 .     Genital  tract,  dorsal  view. 
Fig.  2.     Postcava,  abdominal  aorta  and  right  kidney. 
Fig.  3.     Left  lung,  lateral  view. 
Fig.  4.     Pylorus  and  ampulla  duodeni. 

Plate  LIV. 

Fig.  1.     Skull,  norma  verticalis. 
Fig.  2.     Skull,  norma  basalis. 

Plate  LV. 

Fig.  1.     Skull,  norma  occipitalis. 
Fig.  2.     Skull,  norma  lateralis. 

Plate  LVI. 

Fig.  1.     Skull,  medisection  showing  nasal  fossa  and  dura  mater. 

Fig.  2.     Skull,  medisection,  dura  removed  to  show  cranial  cavity  from  within. 

Plate  LVII. 

Fig.  1 .     Left  mandible,  lateral  view. 
Fig.  2.     Left  mandible,  mesal  view. 
Fig.  3.     Otic  capsule  and  auditory  ossicles. 
Fig.  4.     Cervical  vertebne,  ventral  view. 

TEXT  FIGURES. 

PiOE 

Fig.    1.  Lateral  view  of  foetus .  4QO 

Fig.  2.  Ventral  view  of  foetus 400 

Fig.  3.  Rudiment  of  naso-vomerine  organ 402 

Fig.  4.  Section  of  muscles  of  ventral  pouch 407 

Fig.  5.  Thyroid  cartilage 437 

Fig.  6.  Schema  of  brachial  plexus 471 

Fig.  7.  Hyoid        .                                  .                 484 

Fig.  8.  Sternum  and  first  rib 4gg 

Fig.  9.  Section  of  carpus 491 

Fig.  10.  Pelvis .  491 


500  SCHULTE,  SEI  WHALE. 


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